joining me right now here in washington is nbc news tammy leitner. tammy? >> reporter: hey, chris. i am here with a brother and sister team who i just love. this is daniel and julia. i first met them about a month ago. they both go to school in parkland. you were there for the shooting. i met you on a bus to tallahassee. you're both very active, very vocal. daniel, tell me a little bit about what you thought of today. >> it was such an incredible experience. i love just being there, seeing what everyone had to say about the issues. it was really inspiring. you know, seeing the newtown people really, really did hit hard. i mean, seeing them come out and say we do support parkland. we support you. we stand with you. we want to help you through this process because we've been there. it was very, very moving and touching. i loved it. i loved every second. >> julia, older sister. half a million people out here. a lot of them are out here because of you guys at parkland. what's your reaction? >> it's one thing to see the support online and see people tweet us, like our messages and stuff

. >> for more on what to expect on this extraordinary day, we're going to head to tammy leitner. tammy's just a few blocks from here me along with everybody will be marching and gathering. sop security, i know that's going to be a challenge for both those folks getting into the march but also anybody trying to get around d.c. today. >> reporter: yeah. that's right, alex. heavy security out here. they've already done a sweep of the area. most of the roads in downtown d.c. are closed. they're actually encouraging everybody to leave your cars at home, take public transportation, walk. and that's because there's going to be about a half million people out here walking down pennsylvania avenue eventually ending up where we are today at the stage. there's going to be a rock star lineup out here. lynn manuel miranda, miley cy s cyrus, ariana grande. i can tell you out here where i am, there are already about a hundred people out here. i'm actually out here with fletcher williams and you came out here from north carolina with your dad. i have to ask you, why the heck are you out here so e

tammy leitner is in the crowd for us. re today. >> reporter: i do, brian. i'm here with senator tammy duckworth. senator, tell me what today means to you. you actually fought in the military, but you're in favor of gun control. so talk to me a little bit about today and why you decided to be out here. >> well, i'm out here for my daughter's life and my soon to be born daughter's life. she's about to start preschool. i can't imagine sending her off to school and her not coming back. we need sensible gun legislation. those trained in firearms know that you need universal background checks, ar-15s don't belong on our streets. these senators need to be held accountable. >> reporter: what will it take to get legislation passed? >> the legislation is written, i've co-sponsored several of them. if they put this to a vote on the floor, it will pass. >> reporter: are you surprised to see these kids being so vocal and getting something done? >> i'm surprised but i'm also so proud of them. they're exercising their democracy. and i'm

for "today," tammy leitner, nbc news. >>> yikes. >> you want to go skiing? let's go to dylan out on the plaza. a lot of people. >> wow. look at how big the plaza is this morning. we have people from all over. we have west virginia. we have indiana. wow. this is some crowd out here. this lovely lady celebrating your 60th birthday? >> yes. >> who do you have? >> my sisters. >> it must be st. patrick's day. people are fired up. let's look at the st. patrick's day forecast. it is looking chilly here in new york. 37 degrees. at least it will be sunny. we don't have to deal with rain. in boston, mostly cloudy and colder up there. 34 degrees for the st. patrick's day parade. chicago has clouds and a breeze to keep it 39 degrees. it feels colder as the river is green. savannah. a gorgeous st. patrick's day. mostly sunny and 63 degrees. tomorrow, we will see strong storms in the gulf coast and down south and also across the western texas area with a critical fire risk with the dry conditions. snow moves in the rockies and it will be chilly in the northeast. >>> we've

nbc's tammy leitner, jacob season remov soboroff. tammy, what have students been telling you? >> craig, a very, very powerful day. you know, we had some a-list celebrities here on the stage behind me today. but today was really about the students. about a half million people here today, and i'm actually here with one of the teachers from parkland, melissa, you're a journalism teacher. we've spoken a number of times since the shooting actually happened. you hid in a classroom with a lot of your students. there were about 1,000 of your students out here today. and you must be proud of them. >> yeah, i'm incredibly proud of the students at our school. i was amazed by today's event that they said they were going to do something, and in such a short period of time, were able to organize it and make it happen. and the size of the crowd today was just amazing. and just a testament, you know, to what they can achieve when they put their mind to it. >> reporter: and one thing you were telling me really struck you, they shared the stage with so many other students that have been impacte

tammy leitner, what are you learning about the investigation? chris, if the theory is true, that the would-be assassins planted the nerve agent in a suitcase in russia and never entered the uk, it'll make it more difficult for investigators. we know 131 people could have come in contact with the toxin, novich novichok. officials are taking no chances. the people are all been monitored. though we're ten days into this investigation, it still continues to expand. there are a number of areas in and around salisbury cordoned off. investigators are saying this could go on for months. >> moscow has vowed to, as we said, remove uk diplomats from the embassy, but is there word when it might happen, how the uk would respond? >> as far as the timing goes, we're told this could happen at any moment. it is unclear how many british embassy staff members will be expelled. keep in mind, this is a direct response to british prime minister theresa may's decision to kick out 23 russian diplomats from the uk. a all of this following the assassination attempt of sk

i want to bring in nbc's tammy leitner, standing by for us in london. to be clear here, no evidence currently to suggest that there is a link but here's another death that's being treated as unexplained. what more do we know? >> that's right, craig, we now know that uk's counterterrorism police are investigating this death. although london's metropolitan police are coming out and flat out saying they don't believe there's a link. the cause of death is still unexplained. and police are not officially identifying the victim, although sources are identifying him as ni nicoli glushkov. he sought asylum in uk in 2010. he was accused of embezzling money while living in russia. we do know that he's a former close associate of boris bariskowsky who was a president of putten who was living in the uk and found hanged in 2013 and right now, craig, details are very slim. that is the latest information and it's just coming out. >> okay, again, to be clear, we have another dead russian here in the united kingdom and the circumstances surrounding the death appear to b

tammy leitner is in london to join us. what do we know about this?or purposes of people not following this closely, these are two separate events. >> reporter: that is correct. there is no official link between the cases. but certainly there is a lot of speculation now that nick lie glushkov's death is a murder. according to the pathology the official cause of death is compression to the negotiation. the counter-terrorism command is taking a lead in this investigation because of who he was associated with. and his death came just one week after the poisoning of former russian spy sergei skripal and his daughter. >> and what do we know -- do we know more about that poisoning? >> reporter: a new theory emerged on the nerve agent that was used to poison skripal and his daughter. the u.k. daily telegraph report that british intelligence believe the toxin which is known as novichok may have been planted in the luggage of yulia skripal back in russia. so according to the article, it could have been in an item of clothing or cosmetics or else in a gift that

. >> and while some deal with power outages, our tammy leitner finding another concern for those living on the coast. >> reporter: here in duxbury, massachusetts, parts of the seawall were destroyed during last week's nor'easter, and now residents are wondering if their homes will survive. >> before the storms hit some homeowners working alongside crews to help reinforce the collapsed wall. >> the next-door neighbor and myself went ahead and started doing the repair work. if we didn't do it, within hours of that my house would have been in the ocean on monday. it would not be here. >> reporter: now, new york's governor says the response by utility crews will undergo a full review. on the plus side to a march snowstorm, a lot of this snow will melt each day. however, if you're out after dark be careful, because that melted snow will tend to refreeze and it can become very icy. >> all right, dylan, thank you so much. >>> as the storm hit, as you might guess thousands of flights had to be cancelled on thursday and hundreds more still won't be flying today. national correspondent craig melv