Transcript for Pro-Russian Militants Shoot Down Two Ukrainian Helicopters

-- -- hangs in with their bare hands citizens in eastern Ukraine try to stop the Ukrainian army. From entering their city to Ukraine helicopters -- Palmer shot down one pilot was killed. And on the ground reports of three other other deaths right. The -- but slowly on ski Ukraine. Cutler in New York eastern Ukraine erupting. After the government and he -- -- to take back cities now controlled by pro Russian Alicia. Citizens and militia in the city of Soviets barricading the city -- of tires setting them on fire. And -- fears that Russia may be giving weapons to the militants. After two Ukrainian army helicopters. Were shot down one pilot was killed and wounded and then another taken captive. -- -- pro Russian militants. An ominous statement from president -- -- in Moscow the offensive has quote effectively destroyed. And -- was and quote from any chances of implementing that -- agreements reached in Geneva to defuse the crisis. The BBC's nick Childs has this report on the escalation in Ukraine. Braced for -- missiles. The report suggests the Ukrainian government. Has launched its most determined operation yet to dislodge these pro Russian separatists from their positions in and around the town of civilians -- Raising the tensions and stakes again in the crisis as the Ukraine's unsafe -- And the government forces have already paid a price in this new -- down. These unverified pictures apparently of one of two military helicopters downed in the operation so far. Two Ukrainian military personnel have been killed according to the authorities in Kiev. It didn't boy we had -- the -- and -- -- flying is scary the test as a ringing. It -- ready -- day Easton this man it seems a survive -- from one of the helicopters now in the hands of the separatists. In short -- that we've been able to save one -- and there was another helicopter shot down and we tried to approach that want you know this man was abandoned by his own people. This may look like the most serious government offensive so far off but how follow these -- -- go and what will the fallout be. The air and army -- is blocked by locals underlining the scale of the challenge still for Kiev in reassessing its control. And slid against itself -- reinforcing their defenses should the Ukrainian military try to move in here. That the most of -- Houdini -- standing here to prevent any military people from entering the city. We're protecting our land our children. We're working people were not writer left. We're normal people of the city there are no Russian troops here is they claim. That. -- -- And from the self proclaimed pro Russian -- of the city of video appeal it's under siege he says he -- women and children to stay at home. And men with weapons to defend the city. Kiev says it's not facing just ordinary protestors but heavily armed Russian backed militants and the downing of its helicopters shows this. But Moscow says -- has killed off the latest diplomacy to defuse this crisis it's demanded to holds to what he calls a punitive government operation. -- are we looking down the barrel of further escalation media nick Childs BBC news. ABC's on the -- joining us now from -- yes. With the latest on this Mohamad will what -- situation there. The situation is very intense you know eastern Ukraine is still not just with cities -- smaller towns. And we are seeing what they call self defense units pop up almost everywhere. In fact in the city in. You can see young men who have now started wearing army fatigues. Claiming that they are patrolled the streets in defense of these cities and in defense of all its eastern Ukraine. So it's not just that it's tense. It is also alleged different armed groups being on the streets either very late at night. And there's a very real feeling here again that Ukrainian troops might come in on -- And so a lot of people in this city and in other cities and in the eastern Ukraine are bracing for what could be a major onslaught within the next 24. -- the feeling that this is a civil war in fact on the brink. And I that's a very good question -- -- it doesn't just feel like a civil war today we spoke with a Russian or pro Russian separatist leader who told us unequivocally. This is now a civil -- -- accused Ukraine is issuing criminal orders to send its army in against its own people. And vowing to resist saying that you know it's -- and it's their culture it's their property it's their language is that religion. And they are going to defend all of those things to adapt. When you look through words like that. And the fighting is happening not just in eastern Ukraine but there are some incredible pictures right now coming out from Odessa where basically. Big massive mobs pro and anti Russian protesters collided. And engaged in -- very serious fight. If you look at that and what's happening here in eastern Ukraine. This is very clearly if not already heading towards a civil war. Talk about the intensity that it did in the event in the sense that both of those helicopters were shot down. Obviously there -- must be some kind of response from the Ukrainian government for NATO to have that kind of firepower to be able to take down a government military. Sure well this is something that president double Obama. Alluding to today. You can't just pick up a small little firearm or even a rifle and shoot -- a helicopter and forces to come crashing down it's incredibly rare for that to happen. The Ukrainian government they put out statement saying that they believe. Specific type of weapon a shoulder mounted missile called man pad. Which stands for man portable. I -- the accident but essentially it's. It's the main weapon that was used by asking against the Soviets and it's credited with actually forcing the Soviets out of Afghanistan as little -- -- -- that you can use it aircraft. Those same weapons by the way again that the Syrians have been asking for a fight against President -- -- side. The United States said no because they didn't want them to fall in the wrong hands -- are obviously very dangerous. Well if those are the weapons that are now being used here in Ukraine number one it indicates that these are not a single soldier that are rising -- indicates that they had some very. Had -- firepower and military training behind them. But number -- this is opening up a whole new ways. In this battle if those man -- are being used because it means. Aircraft might not be able to fly over the country in these helicopters certainly won't be able to go it and do you know paratroopers -- so this could very much change it's change the ground in the battlefield. Supplements -- with the US response than because he is not as 600 troops in countries that neighbor Russia. An ABC news chief global affairs correspondent Martha Raddatz interviewed and NATO lieutenant general about the potential consequences. If Russia does decide to intervene let's listen. And and if they. If the Russians and eastern Ukraine it would -- that 600 troops in -- -- What I can -- what you also from woods. The confidence in those countries that. Making a big mistake they -- because they were sent. Holders may not be. Hope they determined they -- real Hillary and a long way think they. This Omaha we hear there the lieutenant general is saying on those 600 troops in the baltics and Poland what they're supposed to do but. You know what -- eastern Ukraine any different from Crimea. What crime you don't forget already -- At least there's there's already Russian presence there is also much easier area to contain. This is an area that's predominantly working class people who worked you know in factories that are now closed. Economically it's not know that the best part of Ukraine essentially people are struggling. And -- -- been given. The short end of the -- -- by the government and he has not just with this new government -- -- that they feel discriminated discriminated against for years. Most of the people here also recently news ancestry back to Russia. Some of there -- parents or grandparents fought in wars that Russia particularly. This is -- -- World War II and Russia's victory over the Nazis in this world. I'm so there are people who identify very very strongly with Russia. And so when you see people saying you know where pro ration that explains why because state they align themselves much more strongly with Russia -- they do you do with Europe or NATO. Isn't there also this was his we have been -- -- for a public referendum in the works much like Crimea but what is the likelihood -- that actually happening. Well it's a good question I would rephrase that -- -- what's the likelihood of a free and fair referendum I'd say that's basically zero. What's the likelihood that this referendum will still take place. Just when it probably say a 100% most of the separatist leaders we've spoken to say no matter what happens even if Ukrainian troops come marching into -- cities. -- -- hold this referendum one way or the other they are convinced that they need to separate from Ukraine that they need to tiny that they need their own independent republics. In order to keep their culture and their likelihood alliance. If what went into over the vote if there was take place and what would if it did take place what -- -- -- then. I think you know it's who we did I don't think there been any scientific polls on which we they would vote. But I think we can expect overwhelmingly that they will vote enables -- quickly disarm their own independent republics. We have also heard of journalists that have been threatened -- one journalist Mike Giglio from buzz feet taking captive. This situation there than as a journalist that it is growing more intense as is and four civilians. It is sure absolutely we we -- cases today where some of our own knowledge ABC -- some of our colleagues were. At a checkpoint trying to go through into the city of slippery -- you ask which is essentially the separatist headquarters in this region. They were stopped at a checkpoint. They had hoods over their heads they were blindfolded they were brought to security building inside the city -- were detained for several hours before eventually being released. Now you know when you operate in this part of world you're getting across certain risks you know there's always -- chance of being detained almost anywhere you go the moment those hoods and put on over your head. That escalated to a whole new level and that's what we're seeing -- right now there is tremendous suspicion of foreign journalists here. Claiming the other journalists are here with an agenda -- -- -- -- -- not not tell their side of the story. And in fact at one checkpoint today what we know what was that -- was a team that went in as a team of 45 journalists only one of them was American. And he overheard that the rebels of the separatists attacked checkpoints saying hey listen if you have any Americans among you we're gonna chop -- -- -- we're gonna chop their how to. So whether they're joking or not as journalists we don't take those risks as soon as they say those words. You know it's time to pack up turner and and go home and that is basically what the situation search -- ABC's on a mile and onions Ukraine obviously safe travels and -- reporting -- we always appreciate that. Mohammed appreciate your time you of course to give up the -- real time by downloading ABC news that starting this story for exclusive updates on the go. You've been watching the international hot spot on -- that's our New York.

This transcript has been automatically generated and may not be 100% accurate.