>>they had some dynamic fire behavior... >> and what we do... don't try this at home! >> tech know where technology meets humanity... only on al jazeera america taking no chances. heightens security over the holiday weekend amid concerns of a possible attack on america greece at the crossroads. as a crucial vote nears on the country's financial future thousands take to the streets for rallies in the capital. >> ominous message inside a

baltimore police van discovered just a few months after the death of freddie gray. now the department says it's investigating. a hidden hazard. >> i can't see people moving in around this toxic land. >> in san francisco, a con to vericy over badly needed housing. are these new homes being built on toxic ground? >> law enforcement at the national mall and other landmarks are watching for anything unusual after a security risk warning from the federal

government. >> officials stress though that this warning is not based on official intelligence. >> this may be potentially the most complex counterterrorism overlay for this event ever. again, that is not driven by any information or particular threat as much as it's driven by the unfolding world

eats. >> the police department tweeted friday afternoon, quote, the nypd harbor unit and thousands of officers will be ensuring the safety of all. in philadelphia, body scans and security checks near constitution hall where it began 239 years ago. >> be mindful of what you're bringing with you and know it's all subject to being

checked. >> greece and europe are preparing for a referendum that could have huge impacts on the continent. on the terms of an international bailout now, several polls show the vote to be very close. rallies took place as greece's highest administrative court ruled that the referendum is constitutional. here's more now from athens. >>reporter: it means no the no campaign gathered in front of parliament backed by the government wants a future in europe but with a better deal for

greece. we're all here to show that we want to be european citizens and that if possible return to dracma. that would be a total disaster. >> of democracy. >> the left wing prime minister believes a no vote will strengthen the national mandate to demand more for less.

>> what strikes me about these two sides is not just the strength with which they're willing to defend their positions but the way in which they illustrate a real division in greek society. one that's being driven much deeper this week. to sign this country up for more austerity levels and to defend what they've got. many here with no jobs and nothing left to lose. >> a no vote for the workers and the young people in greece says that we have to stop all the negotiations for the european union. tomorrow, they will still be my

friend. on this square where greeks have so often demonstrated their protests in the past the no crowd stands with the government of the day. if they win sunday there's not a single person here who truly knows what will happen next. germany will be closely watching sunday's referendum in greece. the euro has been good for the german economy but it does pay more into the european union than any other country. dominick explains. >>reporter: he gives a guided tour around the museum of capitalism. it seeks to explore the issues raised by one of europe's dominant idealologies if the

they have brought problems in southern europe as one by one countries have needed to be bailed out by the eu institutions. in germany, opinion is divided about whether the policies of the euro zone are to blame. eurozone. >> that could be a problem. but in general, i would always support a common currency.

>> the german government has repeatedly stressed its commitment to solidarity across europe and that if the euro fails, europe fails. but one leading member of the ruling cdu party says the eurozone eurozone could survive. >> the situation as it is now p cannot continue because there's no perspective to grow. >> although the referendum will provide a clear view of what greek voters want from the euro zone it will not -- the eurozone, it will not be the end

of the matter. >> iran's nuclear program, one of iran's top officials took to the internet to deliver a hopeful but cautious message. he said that iran and the six nations involved in negotiations have never been closer to deals. we've stressed cooperation, not sanctions could ultimately lead to a final agreement. meanwhile, talks could move past this tuesday's

deadline. >> working through trying to get a deal. remember the interim deal has already been extended extended only until tuesday. time here is running out. there's no prospect for negotiation beyond tuesday. to find a final deal a deal for ten years first and then the period beyond ten years to deal with iran and making sure on behalf of the p5 plus 1, their

same that iran have only a civilian nuclear program. >> from the al-nusra front say the offensive began yesterday. government forces have responded with air strikes and shelling that killed at least 35 militants. the rebels and government forces have divided the city since twelve. also in syria, isil fighters say they have destroyed ancient archeological items from the city of palmaera. they say they caught say smuggler at a checkpoint with six busts and that an intoxilyzer islamic court ordered the busts destroyed and the man whipped. a new wave of attacks by boko haram in nigeria has left more than

100 people dead. >> we now know a suicide bomber was behind the attack a few meters away from a military checkpoint. vigilantes who have been supporting boko haram headed to try to investigate what happened. we're getting a sense of extreme violence that took place. they killed men and boys who were praying in a mosque burned the corpses of those they'd killed. they then attacked people in their homes mainly women and children if the in some cases,

gunning down these women and setting ablaze many homes and businesses in the area. now, this latest violence will be a huge worry to the new government who came to power on a ticket of eliminating boko haram. there's been much diplomatic effort by the new president to try and work out a strategy to defeat boko haram which is involving regional partners in chad and niger. many feel efforts are not going to work. >> a troubling sign in baltimore. the police department there says it's investigating this message posted inside a suspect transport van reading enjoy your ride because we sure will. plus details on the new san francisco housing project that is sitting on toxic ground.

francisco sanchez was in custody in march and was turned over to local authorities on a drug warrant but ice said he was released without informing the agency. previously convicted of vie len lent offenses -- violent offenses. baltimore police are investigating an inflammatory sign inside a police van that has ominous connections to the detect of freddie gray. it says enjoy your ride cuz we sure will.

last year gray was transported in a van just like this one and died. a statement says the nature and location of the warning is both unnerving and unacceptable. his death set off several days of protests. six police officers now face multiple charges including second-degree murder. >> finding a place to live in san francisco is tough. prices are high and the land on which some affordable homes are being built may be contaminated. here's that story now from san francisco. >>reporter: so there is a shortage of affordable housing in this city. is this one of the answers? >> no. no i can emphatically say no. >>reporter: she advises against renting or buying here and she feels the same way about housing on nearby treasure island.

in both places the navy is cleaning up the building and the soil at its former bases. the navy used to decontaminate warships after nuclear testing and conducted radiation experiments on animals here. >> i can't see people moving in here with all this toxic ground around them. they're still cleaning up. that means digging into the ground, lifting up soil breaking up rocks that have everything and anything in it and you're living right on top of it? she lives just about a football field away from the lookout point above the shipyard. she went to the hospital last month. >> i was -- it didn't stop. i was coughing. >>reporter: her father says doctors gave his daughter an inhaler when she had trouble

breathing. it's not clear if the shipyard is the source of the breathing problem but there are toxins here. they can become airborne. >> i know the human outcomes. babies are extremely sick. we need to protect them and get the dust out of the air. >>reporter: the environmental protection agency would not speak to us on camera but a spokes woman says the agency's oversight is rigorous and the navy's own internal routine quality control systems function as designed to do. when the navy has found concerns, it's reported and corrected them. in 2008 a whistleblower reported sloppy work in how radio active

samples were collected. >> the original environmental plan -- >>reporter: robert beck is overseeing the treasure island development for the city of san francisco. he says he's confident the clean up crews under the supervision of the state department of public health are keeping toxins contained as they're transported out of here. >> it's to contain the soil that they're removing which is the concern and as they excavate that and load it in trucks they're covering the trucks wetting down the materials so it's not airborne.

>>reporter: one resident refuses to drink the water. ash . >> whatever it is that affects my daughter's health i'm going to make sure it's taken care of. >>reporter: the reality is with the housing crunch such as it is in san francisco, he may have few alternative places for his daughter to live right now. it's set to become the latest health insurer to -- humana for approximate $35 billion. it would make aetna a major player in a growing medicare advantage business. humana . >> jetblue is expanding its charter flights to cuba. the airline became the first

major aircraft to operate direct flights between new york city and havana. jetblu already -- cuba travel services will offer the weekly flight on fridays from new york's j.f.k.

>> buried where, he began to catalog the lost bodies himself. >> i went and got myself a clipboard and some paper and started walking at a1 and anything close to december 7th, i spent many moons up there.

i went after all navy everything of world war ii that was buried in that cemetery. >> after 40 years of work his crusade helped convince the department of defense to disband its existing department for handling the dead and create a new lab in hawaii for identifying remains through dna. still, the crew of the oklahoma will be an enormous

challenge. coming up on the program, you can call it a stellar landing, the solar powered impulse ii makes a successful landing in hawaii.

sampa aviation history being made in hawaii. the solar impulse ii landing after a five-day trip from japan. it also marks the longest flight ever by a plane using solely renewable energy. the trip powered only by the sun's rays. >>reporter: live pictures of the landing in a plane without a drop of fuel. >> no fuel no engine. but plenty of solar power. enough to keep a plane flying in the air for almost five days. and landing it into the record books. >> it's going to be on all the

front pages tomorrow. taking off from japan monday aboard the solar impulse ii the trip that lasted 5,000 miled ended in hawaii. the single seat plane flew on batteries powered by 17 thousand solar cells attached to its wings and ran on stored energy at night. >> i think i was privileged to did this. it was an extraordinary experience. >> and to the cost of (10)000-0000 over a 12-year period the next era of aviation has arrived >> the project like this one shows that renewable energy is a clean technology and energy efficiency can be reliable can be exciting and can be

profitable and that's all of our time. i'm tony harris. ray suarez is up next with inside story. but for the youngest drivers the digital natives who had a cell known in their hand since they were little, it heightens the elevated dangers for them and other motorists on the road with them. driven to distraction - it's tonight's "insid