happening now, breaking news. two more pings are heard in the hunt for flight 370 and its black boxes. stand by for new information on this critical discovery and what comes next. search leaders are more optimistic than ever that the plane will finally be found. we're going to show you how they're working to close in on the likely crash site right now. plus, high school horror. a teenager goes on a bloody rampage with two knives, stabbing student after student. we just learned new details about the attack and the fate of the suspect. we want to welcome our viewers in the united states and around the world. i'm wolf blitzer. you're in the "situation room." >> this is cnn breaking news. right now flight 370 search teams have four separate signals to guide them as they try to zero in on the missing plane. they're combing the deep waters of the indian ocean hoping to detect even more pings that may be coming from those two black boxes. after a month of false leads,

search officials sound a lot more confident right now that they're finally, finally in the right spot and that at least some of this mystery will soon be solved. our correspondents in the united states and around the world, they're covering the breaking news. along with our team of experts here in "situation room." first, let's bring in aviation correspondent rene marsh for the very latest. >> well, wolf, the manufacturers of the pingers, they believe this is it. the sound from the black boxes. australian authorities have gone as far as they can without actually saying they found it. 34 days since flight 370 went missing, and crews now finally believe they're searching the right area. after 67 hours of silence came 5 minutes of hope. >> ocean shield has been able to reacquire the signals on two more occasions. >> reporter: the elusive pings, they've been desperately trying to recapture, detected again

tuesday. once for about five minutes and then again for seven. ocean shield has now picked up a total of four pings in five days all near the arc where the plane made its last satellite connection. >> i'm now optimistic that we will find the aircraft or what is left of the aircraft in the not too distant future. >> reporter: the detections boosted optimism, but crews are still listening for even more to narrow the search area and they're on borrowed time. >> guaranteed shelf life of the pinger batteries is 30 days and it is now 33 day since the aircraft went missing. >> reporter: investigators say they will only launch the underwater vehicle bluefin after they are certain the batteries are dead. equipped with side scan sonar, the bluefin can launch search missions that last nearly a day, but it's slow. it would take six times longer

to cover the same area as the towed pinger locator. once found, it could take months to recover the boxes. the water in this area can be miles deep. recreational scuba divers only go down about 130 feet. the empire state building submerged would only go down 1,000 feet. light from the surface stops at 3,000 feet. the grand canyon, over 5,000 feet deep, and that still wouldn't even come close to reaching the ocean floor. the titanic was discovered more than 12,000 feet down, but the black boxes are believed to be even further than that. more than 14,000 feet underwater. >> well, analysis of the first set of pings has ruled out, they ruled out at this point that it's from anything other than an electronic equipment. they believe that this is from the flight data recorder. the most recent pings appear to be weakening. the manufacturer of the pingers

tells us based on testing, it should last about 35 days. keep in mind, we are now on day 34. >> yeah. all right. we'll see if the batteries continue to last. they're not going to last a lot longer assuming they're operable. stand by. let's go to perth, australia, the staging area for this massive search. cnn's michael holmes is on the scene for us with more. i guess they're getting ready to take off at daybreak. is that right? >> reporter: yeah, i can hear in the background actually some engines happening, maybe they're going it get going soon here, wolf. it is still early morning, predawn. but re we expect to see another dozen planes out again combing that area. you know, it was interesting, wolf, hearing air chief marshal angus houston saying what he said. this is a man that is very much given to caution. he's not going to raise false hopes. for him to say he's optimistic the aircraft wreckage will be found is telling. rene mentioning there, of

course, even if they do come to a conclusion where they triangulate and think it's time to get the bluefin submersible down there to try the map the bottom, it's a tedious process. it moves at walking space. takes two hours to get it down there. 16 hours of runtime when it is down. two hours to get back to the surface and hours more to get the data off. and also the searchers have no idea really or very little idea of what the seabed looks like. as we've said before, we know the moon surface better than this area of ocean floor. and it could, perhaps, have meters of silt down there which could bury or certainly hide recorders and wreckage. wolf? >> so they've got their hands full. even if they can get some more pings, michael, they still have a lot of work to do because you think about two small boxes in an area of about 17 -- separating maybe about 17 miles, that's a lot of area to search, at, what, three miles deep. >> reporter: yeah, that's exactly right.

and the depth is crucial to this, too. getting that submersible down there. of course, once they do get that mapping and say they are able to find out where the wreckage is, then you've got to get recovery vehicles into place. this is something that is not going to happen quickly. this could take months before they're actually bringing anything up. if, indeed, they do find it. and what they're doing at the moment with these pings, and dragging that ping locator around, the multiple pings they get, this isn't a directional device. it just sort of picks up the sound and then they try to get another sound from somewhere else and triangulate it down the way you would with, say, a cell phone or something to try to get a more specific area and then they'll put down the bluefin and try to map it out and see what they can find in terms of wreckage, if it's there. and it could have moved around. been a lot of storms lately in the area, and the like. there's a lot of factors at play, but the optimism of the air chief marshal is really quite telling, i think. this is not a man given to

hyperbole. >> he's optimistic. not cautiously optimistic as he said a few days ago but he's optimistic right now he says. michael, thank you, michael holmes in perth, australia. aviation correspondent rene marsh is with us as well as aviation analyst mark wice and peter goles and law enforcement analyst tom fuentes. how chose are they, mepeter to finding the two black boxes and plane? >> they're closer but not close. this is still a long struggle. four pings 17 miles apart. they've still got to narrow it down. if the pings die out, we're in for a long slog. so i'm optimistic as the vice air marshal is. we're in for a long fight. >> you think this could take weeks if not months to locate the two black boxes. assuming they locate the black boxes, they're assuming there might be wreckage there as well. >> if they can see them. the silt could be thick enough the box has sunk into it and the

currents maybe washed over. it's almost like finding buried treasure on top of everything else they're looking for. >> are you hearing, rene, that the pings are coming from the flight data recorder, not the cockpit voice recorder? just just one of the two boxes? earlier a few days ago we heard authorities say that australia they think they had two separate pings which would indicate they're come from two separate locations, two separate boxes. >> now, i did hear angus houston say that. he specifically said after analyzing the pingers, they are consistent with the flight data recorder. now, i believe that he's speaking in general terms. that it's consistent with this piece of equipment, not necessarily the flight data recorder versus the cockpit voice recorder. i think that he was just speaking loosely at that moment. >> because earlier when they found those first two pings, mark, as you remember, one lasting for about two hours, one lasting for 15 minute, they were

in different places. at that time he seemed to suggest they were coming from the two separate black boxes. >> absolutely. you know, if it is only from the flight data recorder, remember the cockpit voice recorder has a two-hour loop on it. you're going to get a lot of information from the flight data recorder, particularly if there was no real conversation going on going on in the cockpit. >> this is the flight data recorder, peter, as you well know. this is the little pinger over here that sends out those critically important pings, those signals thalts would help to try to find this. and the matter of the depth, no matter how long it's down there, the information in the flight data recorder will be useful to investigators. >> it will be useful and it is the most critical. as mark said. the voice recorder may not have information that we can use. the data recorder will be invaluable. and, of course, the other challenge is, it's not uncommon for pingers to become separated from the box, themselves. >> the actual pingers. >> that's right. >> let's hope if they find the pinger, it is part of this

device right here. hold on for a moment because i want to bring in another aviation ex-per, jeffrey thomas is joining us now live from perth, australia. he's editor and chief of airlinerating airlineratings.com. what's the latest you're hearin perth? they're pretty upbeat, pretty encouraged, aren't they? >> indeed, wolf. they're very, very encouraged. and as michael had said earlier, angus houston very, very downbeat sort of guy. he's really upbeat. the verbiage coming from him. but behind the scenes, i'm hearing lots of good things. they're very, very confident because where the ocean shield is l has located the pings is where inmarsat telecommunications company said they received the last handshake from this 777 in this very location. also ocean shield is looking on the flight path that the international team of experts

had worked out that the plane had traveled. now, the other thing about this is ocean shield is searching in one very small area. the rest of the search fleet is about 500 nautical miles approximately to the west. that's because they're searching for debris on the surface. now, about two weeks ago approximately, a tropical cyclone, a hurricane if you like, jillian, traveled south and then right through this area and then turned west. and they believe that the debris has been dragged to the west of the actual crash site and that's where they're looking at the moment for some surface debris that would absolutely give them confirmation. >> if the black boxes, though, jeffrey, were in that other location within a 17 miles, let's say, of each other, wouldn't -- i assume they're under the belief that there's at least some wreckage, some heavy equipment that landed at the bottom of that area as well. let's say engines, for example.

>> look, indeed. i mean, the substantial part of the airplane is absolutely underneath the ocean shield somewhere. but what they're looking for as well are some floating debris that they can pick up and say, this is definitively mh-370. we absolutely know we're on the money. because they're 99% certain that they've located the black boxes, the pings, but they want absolute proof that they found this airplane. >> when you speak to them behind the scenes, geoffrey, the searchers, what do they say about this mystery that they haven't located any debris, any debris at all from the plane? >> well, look, yes, good question, wolf. one of the problems, of course, is we're now into day 34. if we had been looking in this location day one, then we probably would have found debris almost straightaway.

but don't forget, we were a week in the south china sea, then a week and a bit well south of this location on the initial analysis done from the satellite pings. this particular search area, the ocean shield has only actually been in this area for eight days. so the oceanographers that i speak to, the crash investigators that i speak to, suggest that, you know, any wreckage, any floating wreckage would have been -- would have sunk now through this tropical cyclone that came through about 10, 12 days ago. and that's why they're not sort of picking up something instantly, if you like. >> you know, tom fuentes, you're a former assistant director of the fbi. you used to work closely with other international law enforcement types including that malaysia. even if they find these black boxes and they twin to tbegin t determine what was going on

inside the cockpit, are we any closer right now to knowing why these plane supposedly wound up where it did, the southern indian ocean over there? >> well, if the voice cockpit recorder is blank and written over, there's nothing new on that, it's still going to be a very difficult problem. now, the other aspect is, when the forensic teams, if they're able to get to the cockpit on the bottom of the sea and determine through dna checks who's in the cockpit, that might lead to the information. if it's just the pilot and co-pilot who you expect to be there, that will be one thing. if there's some unknown person that somehow was in that location when they find the victims at the bottom, that will add a new dimension to this. so far, nothing new has really come up. they're really hoping for some information from the crash. >> the suspicion, peter, as you well know, still on that cockpit r crew, if you will, especially the pilot. that's what malaysian authorities have suggested. >> i think we've been in agreement that this plane was directed by humans to this spot.

why it was directed and who did it, that's the mystery. >> is there any way this could have been a mechanical failure and the plane was just on auto pilot and wound up where it did? >> that's a good question, wolf, but, you know, if you take a look at what these supposed tracks have been on that, when you put the information in on the computer on the ground in kuala lumpur, it would have followed a flight path that would have taken it up to beijing. the turns off of that flight path had to be done by human input. so, that's where the flight data recorder will come in. you'll be able to tell how many times that was done. >> have you heard anything, rene, about when they think the batteries for these pingers here are definitely going to be dead, and they will then send down the submersible equipment? >> well, the manufacturer told us based on their testing, 35 days, so, again, we're on day 34. however, you know, he wants to go on with this until there's no we that the batteries are dead.

so i would imagine he would stretch it to maybe 40 days. 42 days. just to make absolute sure that there's no other chance that this thing is still pinging. and to your point, i mean, that's why they haven't given up on the debris, because if that is overwritten, the debris can tell us a big story here. as to was there an explosion or anything else? >> you know, geoffrey, let's not forget, i want to give some perspective here, because you're speaking to authorities on the ground over there in australia. let's not forget they found debris on that air france jetliner off the coast of brazil in the atlantic ocean in 2009 within 5 days, but then it took them at 2 years to find those 2 black box there. is that what we anticipate could happen here? >> well, that's an interesting question, wolf, because my understanding is that the black boxes didn't -- we didn't get pings off the black boxes. now, i could be wrong. >> no, you're right. on the air france, there were no

pings. >> yeah. >> there may have been pings the first 30 days, but they missed them and then they were just searching and searching and searching without any help from pings. >> look, indeed. so this is why angus houston is wanting and commander marks is wanting to stay with the pinger locator to try and cut down the time we need to spend on the bottom looking for this. but, indeed, i mean, we're looking at a much greater depth. we're looking at an area which we know very little about on the bottom. so it is going to be a real challenge no matter how accurately we triangulate this, it is still going to be weeks, maybe months, possibly longer, before we're actually able to locate the wreckage and black boxes. as has been said earlier, this particular location, the silt on the bottom is approximately 60

feet deep. so very heavy, small objects will sink well into that silt. an object with a large, flat surface will not. it will sink slightly. a very heavy, small object would sink, so a lot depends on how the airplane is broken up, whether it's remained in tact or being shattered. that will play a big part. >> certainly will. jeffrey thomas, thanks to you as well. thanks to our panel here in d.c. we're going to stay on top of this story, obviously, for our viewers. still ahead, we're going to show you how those new pings are helping search crews narrow the target area and hopefully find an actual crash site. we'll talk to the man whose company developed the locator beacon used on flight 370. does he believe those new bly discovered pings are from those two black boxes?

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crossfire won't be seen tonight so we can bring you more of our special coverage of the mystery of flight 370. right now searchers are triangulating the latest pinger signals in an effort to try to find the plane. cnn's tom foreman is here with a closer look. so explain what this means. this triangulation that they're trying to come up with. >> very simple term, wolf, what it means is they want as many hits as they possibly can from these pingers. from these flight data recorders to help point them in the right direction. so think about it, this is that big southern arc defined by the satellites we've talked about. as you move? here, this is the actual path followed by the ocean shield.

they're looking for these pings. look where they picked up the pings along the way here. in these four different areas. this is separated by about 17 miles. so altogether, still a pretty big search area. around 560 miles off in. but what they're doing here, this may look chaotic, they're imposing an order upon the pings. the idea is you go out and create a grid in the ocean by sailing back and forth one way, then back and forth another way. and every place you can get a ping you record it and then you look for the commonality. where did you get the strongest pings in both directions? and if you get that, then you get a much smaller box than the big one out here, wolf. and that actually matters because once you go into the ocean, and you start looking for this, you need a much smaller area to work because this is a very forbidding environment. at the lowest area here on this slope they're working on here about 1 1/2 miles, down at the

bottom, more than 3 miles, this looks likes it may be around the 2 1/2 mile depth. but that, as you know, wolf, from all of your reporting, very forbidding depth. a difficult place to work. you want to be as close to your target as possible before you go down and start looking for it because it's going to be a long, slow process. >> yeah, we should be hearing fairly soon whether or not they found any more pings out there. tom foreman, thanks very much. the new narrower focus follows weeks of searching marred by missteps. cnn's athena jones is here with us, part of the story. so what's been going wrong? >> well, wolf, by all accounts there have been a lot of bits and starts in this investigation with missed clues and distractions. like those debris sightings we've been hearing about for a couple of weeks now. those detours have cost investigators crucial time. it's the most extensive search ever for a missing commercial jetliner. >> we are trying to do everything in our powers to find where the plane is. >> reporter: and it hasn't been without detours.

hundreds of miles of ocean searched. thousands of miles apart. and poorly coordinated at the start. >> it took weeks for those people to be able to be assembled and organized. >> reporter: after learning the plane lost contact with air traffic controllers at 1:19 a.m. on march 8th, search teams spent much of the first week looking in the gulf of thailand and the south china sea. four days into the search, new analysis of radar data showed the plane changed course. taking a sharp left turn. had this data been analyzed earlier, it could have saved pressu precious time. a breakthrough, british satellite company inmarsat calculated the plane flew for several hours after losing contact. >> the plane lost communication with a satellite was at one or two possible corridors. >> reporter: a northern arc and a southern one. further analysis ruled out the northern half but not before teams spent several days searching there. once the focus shifted south,

satellites and planes from half a dozen countries spotted hundreds of pieces of debris. that seemed promising, but the debris turned out to be fishing equipment and ocean junk. >> unfortunately, all the leads we got from the satellites turned out to be other things other than wreckage from the aircraft. >> reporter: now searchers are optimistic. still experts caution we're not there yet. >> that's a large area of ocean. it's going to take not only expertise, but it's going to take some luck as well. >> and one more thing, remember those pings the chinese detected over the weekend potentially from the plane's black box? are those another red herring like the debris sightings? well, teams are still searching that area, but it's clear the four signals picked up by the australians over the last few days are now the main focus. >> athena, thanks very much. let's bring in correspondent richard quest who's been covering this story for us.

ri richard, investigators say they feel optimistic, not cautiously optimistic any longer. they say they're optimistic. we know they've been wrong before. are they overeager or do you think this is really it? >> i think these men and women choose their words very carefully, wolf. one military man said he's respectfully optimistic. another one says, i mean, listen to angus houston last night. and i think that the way he put it, he will not go that final leg and say, this is the place, until he has seen real hard debris. and he says that because the families deserve the closure and the closure only comes with the certainty. but you have to be -- there comes a point, i think, when you've got to say when you'vera experts saying it is not -- it's manmade, it's electronic, it's 1.106, it's in the right

frequency range, and it is consistent with a flight data recorder. it would be perverse of nonexperts like me to say we think they're wrong. >> good point. richard. our chief national security correspondent, jim is in beijing with the secretary of defense, chuck hagel. they spoke about this search. listen to what the defense secretary said. >> it's an immense search area. we think it's been narrowed, but i can't give you a forecast on what they may come up with, what they may not. there's been some new evidence here that maybe these new and emerging sounds will lead to something, but it's important we don't lift anyone's hopes, the families of these passengers in an unfair way. >> good point by the defense secretary, because those families, as you well know, let's not forget 239 people were

aboard that airliner. those families have certainly been understandably devastated. not only by what has been going on, but by the false hopes that have been coming up from time to time. >> yes, and i think the false hopes are inevitable, albeit they're distasteful and unpleasant and heartbreaking, because this has got such scrutiny, wolf. i've never seen anything like it and i've been covering plane incidents for 25 years. and the truth is, i listened to the last report, and it's very easy for the critics to say, time was lost, money was spent, the wrong decisions were taken, they searched in the wrong area. but this is all being done with a magnificent wisdom of hindsight. i've got an entire file here of that which was happening day by day with the information that was taking place. when you review it, wolf, yes it was chaotic and it was confused, but the plane wasn't where it

was supposed to be, and the information had never been seen like this before. so pulling it together, wolf, i think that the way in which they have moved forward, and the australians have done a stunning job, to be sure, the edge of science. i think what we are now seeing is the closest to resolution and i think you're going to see it happen sooner rather than later. >> when do you think, realistically, they're going to put that bluefin, that submersible device to try to find wreckage actually into the water? >> houston said the signal is already getting weaker. it's already dying. the batteries. therefore, i think, and this is just a guess from listening to what he said and talking to the experts, you've got two or three more days where each day they get a signal will elongate that time period another day. but once they haven't got anything for two or three days, the auv will go into the water.

and i think you're probably talking maybe a week, certainly less than ten days. >> i know that the aerial search for debris on the surface of the indian ocean continues, but realistically they've really searched that area a lot. you think they're going to find anything floating? >> yes, because -- i don't know is the short answer, but here's the really interesting thing. as they've narrowed the area that they're interested, because of the inmarsat analysis, the pings, so what houston said last night is he can send more planes in a more targeted area to those areas where they -- they're not scattering along arc anymore. they know where they want to go. remember, they are forward drifting now. forward tracking. before you wanted to get the -- you wanted to get the debris and then narrow it to the plane. now they believe they've got the

plane and you're widening it to find the debris. so that i think is going to give some hope to that. it's another -- anybody who's sitting here saying what a dreadful job everyone's done should just bear in mind they've not found one piece of debris and that, wolf, tells you how hard this thing is. >> certainly does. richard quest, thank you very much. see you back here tomorrow. more of the breaking news. coming up, i'll speak about these new underwater signals with an engineer who helped make the beacons on flight 370. and another breaking news story we're following. the mass stabbing at a pennsylvania high school. police have just revealed it was even worse than we first thought. we have new details of the two dozen victims. we asked people a question, how much money do you think you'll need when you retire? then we gave each person a ribbon to show how many years that amount might last. i was trying to, like, pull it a little further. [ woman ] got me to 70 years old. i'm going to have to rethink this thing. it's hard to imagine how much we'll need for a retirement that could last 30 years or more. so maybe we need to approach things differently, if we want to be ready for a longer retirement.

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we're following breaking news about malaysian sairlines flight 370. voice and data recorders, the so-called black boxes. let's get more from colleen keller, senior analyst with the consulting firm of metron. she worked on the search for air france flight 447. also joining us, jeff, director of engineering for the company that made the underwater locator beacons used on flight 370. guys, thanks very much for joining us. we heard these pings, the newest two reportedly near that standard frequency. here's the question.

are you 100% convinced that these pings are coming from at least one, if not both of the two black boxes? >> well, it's difficult to be 100%, but our confidence level is high. >> what does that mean, like 99%, 98%? you're almost 100% convinced, right? >> yeah, we don't want to rule out the unthink bable, but our confidence level is high. >> what could it be at that specific megahertz and that frequency, if you will? >> well, we don't believe it's anything that's natural. it's something that's manmade. we don't know what's down there, so we just don't know. we don't know what we don't know, but definitely the signal that the beacon produces is simple and unmistakable, and it's consistent with what they're hearing out there. >> colleen, do you think it could be anything other than the beacons, those pings coming from at least one, if not both of the black boxes? >> no, i agree with jeff. i mean, this was designed to be

a unique in nature. there's nothing else that mimics it. i won't say 100% either. i understand his uncertainty -- his hesitation. but i think we're pretty certain that we're on top of this target. >> are you under the assumption, jeff, that the beacons, those pings are coming from only one, either the flight data recorder or the cockpit voice recorder, or are there two separate beacons coming from both? >> it certainly could be both. i believe one of the first acquisitions at one point they thought they had heard two asynchronous or two pulses that were not sichk nicynchronized w other. if that's true, that would be indicative of both beacons transmitting or hearing both beacons. since that point, i believe they've only heard one at a time. that means either they were not both in the same range or possibly one of the batteries has expired. >> that's possible. i want to talk a little bit more about those batteries in a

moment. but colleen, how many more pings realistically do you think they need to triangulate, if you will, and get a much better location of where the box or both of those boxes are? >> well, i mean, every second, every new ping that we get, wolf, puts us that much closer and will save us time when we go to the underwater search. but really if you think about it, we don't know what the bottom looks like yet, and i was thinking about this earlier. imagine if one or two of these boxes landed in a canyon or some kind of enclosed area, you're actually getting echos of the sound off the walls of the canyon. people have a hard time trying to understand or get their hands around how you can hear the pings really clearly and then you move away and come back on another tangent and all of a sud en you don't hear them for days. imagine what the bottom, topography is doing to the sound, maybe you can begin to understand you might only get certain angles where you hear

the sound and some instances where the sound is traveling unobscured but other cases you don't. >> jeff, what do you think of that theory? >> that's certainly true in the case of air france as well. i know that they did not hear the pings, but the train there was very, i guess, mountainous is the way to say that underwater. so we know that the sea floor is not flat there. >> what's the longest you think those batteries could last, jeff? >> so our official answer is 30 days. the design margin is about 10% above that, and that's at the end of life or that's at the end of the six-year maintenance period. we do have design margin in it and there are varying efficiencies of the product, itself. so we feel, you know, 33, 35 days is not unreasonable to expect. but once it does reach that point, the intensity of the signal that it gives out will start to diminish. it will start to become more and

more quiet, if you want to describe it that way. what that means if you have to keep getting closer and closer and closer to it to hear it. >> this is now day 34 of this search. that's about the point those batteries are probably going to die out. all right, guys, thanks very much. jeff, colleen keller. we'll continue our conversations. we'll have more on the breaking news just ahead includiinclude ing another major story we're following. mass stabbing at a high school in pennsylvania. we just learned of even more victims and what witnesses describe as a bloody rampage. plus, we'll have more on those new pings that have searchers increasingly optimistic about finding flight 370. what can i do on a $7 a month android plan from tracfone? check the weather. borrow ted's wheelbarrow. post big tomato pics. buy a birdhouse for sparrows. download gardening apps. answer my wife's texts. search how to sculpt hedges into a t-rex. i can do all that with my android from tracfone for as low as $7 a month.

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our white house correspondent is there at ft. hood. michele, tell us how this all went down. what did the president say? >> reporter: hi, wolf. today hundreds of soldiers gathered under this cloudless sky in the texas heat. some of them, you know, at one point it was so sigh leapt before the ceremony began that all you could hear from the flapping of flags at half-staff. among those soldiers, some of the 16 who were shot on april 2nd. their families, also families of the three who were killed. the president and the first lady spent about two hours with those families before he delivered his remarks. it was an emotional service. i mean, at one point, they read out roll call. reading each of the soldiers names. for some of them, there was no response except for the families' emotions. the president eulogized each of them. remember, this is the second time in five years he is doing this in the same place. he talked about their sacrifices for their country. we learned a little bit about

each one of them. one was engaged to be married. one months from retirement. two of them had served about 20 years in the army. multiple tours of duty overseas. and the president broached some subjects we weren't sure he would hit. here he is. >> our open society and at bases like this, we con never eliminate every risk, but as a nation, we can do more. to help counsel those with mental health issues. to keep firearms out of the hands of those who are having such deep difficulties. >> reporter: the white house had said earlier that, of course, this wasn't the time or the place to get into politics or policy on gun violence in america. but, of course, the president had made his stance on this very clear. remember last year he signed 25 executive actions on the

subject. recommendations, things like directing the cdc to study this issue. or enhancing the and they also said the president remains extremely disappointed that the congress, as the president said has failed to acton wishes of the vast majority of americans in expanding background checks. they said the president was heartbroken and saddened to be here again. i think among many of the families, it was really the mental health issue that hit home among the remarks he made. we talked to one army wife who said people in her have suffered after tours of duty. and as she put it, more soldiers here do need to be helped. >> an emotional memorial service today fort hood. michelle, thanks very much, michelle kosinski reporting for us. we're also following another breaking story, a heartbreaking story, mass stabbing at a pennsylvania high school. police now say 24 people were injured in a bloody rampage. the suspect a sophomore. witnesses say was armed with two

knives. pamela brown is in murrysville, pennsylvania. that's not far from pittsburgh with more on what happened. pamela? >> we're getting some new information, wolf. we just received the criminal complaint for this suspect. as you mentioned, the 16-year-old male sophomore. and according to the criminal complaint, he has been charged with four counts of criminal attempt, criminal homicide, 21 counts of aggravated assault, and one count of weapons possession on school property. and also according to this complaint, he had two kitchen knives about eight inches long. two steel kitchen knives, wolf. he came into this school early around 7:00 a.m. before classes even started. and according to authorities, he went through the hallways into classrooms, wielding these two knives, stabbing anyone that went by him. >> i've got multiple victims here. we need ambulances here as soon

as possible. >> reporter: chaos and tragedy this morning in murrysville, pennsylvania. a 16-year-old ran into classrooms on a horrific stabbing free. >> i can tell you what we saw when we got there was a hallway that was pretty much in chaos, as you can imagine. a lot of evidence of blood on the floors in the hallway. we had students running about, trying to get out of the area. >> reporter: one adult and 19 of his classmates were hurt, most of them teens ranging from ages 14 to 17. several are in critical condition, but are expected to survive. >> i was walking over towards the exit, and there was blood all over floor. thought someone i knew was bleeding or something. and someone yelled she got stabbed. >> reporter: area hospitals are treating victims for stab wounds to the torso, abdomen, chest, and back according to medical

officials. >> i would say that half of them are life threatening. >> reporter: it could have been worse if not for a few who are being hailed as heroes, like one quick-thinking student. >> students who stayed with their friends and did not leave their friends, cafeteria workers who automatically just reactively began caring for students who were bleeding. >> reporter: a school security guard seen here also helped subdue the alleged attacker after the assistant principal tackled the suspect. the officer, known as buzz was stabbed, but is doing fine. murrysville's police chief credits a fire alarm with helping to save lives. parents scrambling to pick up their teen students, all of them understandably shocked. >> then i saw people holding each other's hands. i saw all the people getting cut. just blood everywhere. it was very traumatizing. >> reporter: the suspect, being seen taken from the police

station has been treated for minor injury, including cuts to his hands. so far there is no indication of a motive. and wolf, we are just getting new information here about this suspect. we are learning the name, alex riebel. it's alex riebel. he has been charged as an adult, wolf. let me go through the charges with you. four counts of criminal attempt, criminal homicide. 21 counts aggravated assault. one count of weapons possession on school property. so, wolf, that is the latest. we know that the fbi has been searching his home in this neighborhood and nearby neighborhood close to the school. they have confiscated his computer. they're just trying to figure out a motive at this point in the investigation. >> terrible, terrible story that is. all right. thanks, pamela brown for that report. just ahead, we'll have more on the breaking developments in the search for flight 370. our several coverage continues in a moment.

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we're following all the breaking developments in the search for flight 370. experts are analyzing two new signals detected deep in the indian ocean. they're trying to determine if they are indeed from those missing plane black boxes. searchers have picked up a total now of four pings since saturday, and they're all within a 17-mile area. the man coordinating the search says he is now optimistic the plane will be found in the not too distant future. it's the most confident sounding statement yet in the month-long hunt for the plane. that's it. thanks very much for watching.

i'm wolf blitzer in washington. remember, you can always follow us on twitter. tweet me @wolfblitzer. you can certainly tweet the show @cnnsitroom. "erin burnett outfront" starts right now. next, breaking news in the search for malaysia airlines flight 370. a massive change just announced in the search area. and two new signals that could be from the black box. plus, the man who discovered the titanic wreckage. does he think this is it? and our other breaking news story tonight. more than 20 students stabbed at a pennsylvania high school. we have new details coming in at this moment about the teenaged suspect. that's coming up. let's go "outfront." >> good evening. i'm erin burnett. out front tonight, breaking news in the hunt for malaysia airlines flight 370,