Transcript for Soldiers heading to scene of poisoning attack in England

Everyone Terry Moran here would ABC news and I'm in Salisbury. England. Charming small city not far from Stonehenge but right now. The center of a global mystery you might of heard about it. A man in certain guys cripple. 66 years old who was a colonel and Russian military intelligence a rested in 2006 in Moscow for spying for Britain. And then traded. In a spy swap moved here to Salisbury this charming town back in 2010. Last Sunday he and his 33 year old daughter yulia. Were struck down. Nearly died there in Tacoma still. And it has been determined by the British that it is a some kind of assassination attempt using. A nerve toxin a nerve agent like B acts or Sarin or maybe even something more exotic than that I wanna step you through. Basically the crime scene this is what happened last Sunday afternoon. If the focus of a widening investigation into. Perhaps an act of international. Terrorist. We begin here right back here that VV restaurant. That is where they had lunch on Sunday afternoon father and daughter. And then without showing any symptoms or signs out they came here. There were gonna walk down inside here into this passage way this is shopping mall in the middle of this old town. And you may have seen if you've been following this story on the news there's a clip of what might be. Script ball and his daughter. Walking down this passageway. He had apparently. Was convicted in Moscow of giving up several of Russian agents in Europe. To Britain and that's why he was arrested interest in fact at the time that he was released in exchanged. In that spy swap sent here. Back to England where he settled in Salisbury. Vladimir Putin's. Held a town hall and he was asked about this five's that had been traded and he said that this is almost a direct quote. They will kick the bucket trust me they betrayed their colleagues their Brothers and on its. They took thirty pieces of silver. And are gonna choke on all that so is a kind of a gangster threat almost. From the man who at that time was the prime minister of Russia. And the concern is he may have followed through caring. Someone carried out a chemical weapons attack somewhere in here so after wanted the Italian restaurant. The ex Russian spine daughter walking down through here. As it is the quiet city. A lot of people come here is magnificent cathedrals that says this or not far from Stonehenge. And he had settled here everybody knew. Consider them a quiet. Retiring gentlemen. I'll show you something here that picture you've seen it of the two. Was captured by this closed circuit TV camera right here in this him. That shows these two people who are. Persons of interest it's so Fuzzy can't quite tell if it's cripple and his daughter. And interesting factor that one of the woman in that picture is carrying a red bag which was found as they came out of this passageway. They crossed this bridge. The River Avon has called a mill walk this whole part of town been developed and they collapsed. Over here. In this parks or somewhere between them the distance we've just walk between that Italian restaurant. And that park bench which is now covered by a tent. There were overcome struck down. And we're fighting for their lives. Already this toxin this nerve toxin. Just charges the nerves. It impairs breathing right away it shuts down the system it's it's one of those deadly kinds of poisons in the world. They did survive though thanks to some people who saw them in distress on that park bench. And called emergency services police officer responded he himself was hospitalized somehow contaminated by that toxin that. It's persisted that stays on close it stays on objects. And they were stabilized. However there are still in very very critical condition indeed as the investigation widens though. It started here this police cordoned the tent the other gonna have to somehow clean up that area. But it's gone to other locations now not just the restaurant not just the downtown. It's cripples home has now been cordoned off along with a couple of blocks around it. And the similar kinds of tests people in Hazmat suits. Suggesting. Because that police aren't telling where this investigation is heading that it's possible that. Toxin a poison that was used it to attack them. May abandon in his house somehow he may have taken it or or may have ingested it there. And had a delayed effect or something along those lines the one thing we have been told is that. It isn't your standard chemical weapons it isn't the VX are fair and that say Saddam Hussein. Was producing it seems to have been more exotic rarer. Is what we're hearing out of the government. So his home has now been shut down. Another even more chilling possibility. The cemetery. Where his wife is very. It's after a surrogate scruples wife died in 2012. Her grave has been cordoned off. And there are reports today. That her body has been exhumed which raises the utterly chilling possibility that. There's concern that the cancer that killed her. Might not have had a natural cause maybe that was also. Part of some kind of revenge or something against its fairly his 43 year old son died last year. As well so he is right now fighting for his life with his 33 year old daughter and the focus of this. International investigation we should say right away. Russia has denied any involvement in this. I they have said that that this is just propaganda and hysteria. And that there hasn't even been a proper investigation yet and so there's no way they can be blame. The British have a troubled history. With Russians. Here in this country who died mysteriously. Or not mysteriously the most famous infamous example men and Alexander with an ankle back and 2010. Was struck down in a hotel in downtown London. With the radioactive poison polonium one of the most toxic substances on earth the terrible way to kill someone. First it contaminates every where it goes. And second. It takes an excruciatingly. Long time to die as if you've burned from the inside they really want to get after him. The pinnacle was this spot through the dissident. He was trying to expose corruption in Russia. And a British inquest. A formal investigation into the his dad decided that it was the Russian government and the the person in charge of that inquest said. That killing was probably approved quote probably approved by Vladimir Putin himself. So now. Just over here. A former Russian spy who it given secret to Britain. Struck down with his 33 year old daughter. With this nerve toxin. It has raised tension. In the country between Russia and Great Britain I'll say this though walking around today it hasn't really raised a lot of tension you can see. Among among the people of Salisbury we're just a few feet from where one of the deadliest poisons in the world seems to have stricken. Two people. There shoppers we talk to folks who come in from out of town and bring their kids today they don't have a great deal of concern back. And as sure of course again. Would elect talked ABC news in America. With your beautiful are you what I know you'll. I just decades have one question. I am the North American man that's that's a blessing and a curse. We're just just a few feet here from where that Russian spy and his daughter were some were struck down a department. Are you concerned at all do you have any complete Rumsfeld for a first. I. Yes it hasn't found it I the need such as the government has anything that we keep it right. I'd still thankful that this. They. Time. Anyway. So you feel that the government's got a good good grip on them. It hasn't been as Russian. And beautiful but David. No heat and it does seem just to me a few days ago the government was saying. Everybody in Salisbury it's safe we've got situation under control and today. They sent the military. He having read about that it sounds like. Neck. The resource is coming to help get rid of things that. You know I probably shouldn't be used. Anymore and like ambulances I think this what this thing. Business there ain't that vanished exactly six I'm not. That movie just staying gaps in accident they. So it's just me is. This is kind of the British stiff upper lip and here yeah Kerry he called Canada and at. Thank you very much. You. You live by. You do see that you see this this columnists in the face of what pretty severe chemical weapons attack. Right over here or at least woods were the victims ended up and I did mention that the military has now been sent here a 180. Royal Marines. Eighteen trucks chemical warfare gear and apparatus because they need to scrub the sites. Where script ball and his daughter war. Which would include right here this park bench and and placed around you think. His home that cemetery he and his daughter had visited the grave. Of his wife and his son and late from flowers there. So there are increasing numbers of cites it seems. Where they wanna get that they want to scrub it they're looking for clues. Right now there are big questions first obviously. Who did it but before you get to that. What precisely. Was the toxin that was used how was it delivered. You may remember that in Kuala Lumpur for last year Kim Jong who owns half brother can from Nam. Was killed in the chemical weapons attack the wind that was delivered. Two young women approached and each with a claw and they apparently had. Some kind of material on that plot that when combined created a nerve toxin so they rubbed his face first one rugged than the other of the he added. I happen how 45 minutes something like that to the severity. I hear they don't know how was delivered wasn't in the mood today didn't seem to have been. Did somebody encounter them there are cameras all over the place that police kept. Hobart up quite a bit of all of that cctv footage that they can find. What was it something that perhaps his daughter who was visiting from Saint Petersburg in Russia brought with her. Was there some other method of delivery. And one of the questions that people here do one. You know is that is that still dangers here is that person still in the country he still he or she may still around in this area. The question come fast and furious and what started out as a very local. A very localized problem now seems to be expanding. Two. The park today that the bay where they parked the ambulances. And there were concerned the ambulance that where they were transferred might have been. It contaminated so this is a mystery and also an international incident. One thing that that is absolutely certain about Vladimir Putin those who have opposed him those who have betrayed him those who have tried to expose. Corruption especially his. What is alleged to be his personal corruption. Many of them end up dead. It is not a good idea last night on Russian TV. A smirking news anchor note it's hard to imagine that looking let him if you are but a smirking news anchor. Coming out of report from this very place that you know. Big traders in the very good line of work is it and Great Britain is that are safe place to go it if you're thinking about retiring there almost laughing gloating over the fact. That at least Russia is suspected right now. Smuggling some kind of very advanced nerve toxin weapon. And killing and attempting to assassinate people here he found that funny. Old saying about about Russia's that she'd rather be feared than loved and I think right now that is something that Vladimir Putin. Has a reputation he has earned around the world. He is. Someone who has demonstrated on the world stage and cry me and Ukraine and elsewhere that he'll take what he can given the opportunity. What he believes is Russia's rightful. Opportunities he would say and perhaps even order as the British government itself found in the death of Alexander the to make up the killing of people who displease him in other countries. That's where we are in Salisbury England. Charming city at the heart of this global mystery and international. And that's all from here Terry Moran. With ABC news in Salisbury.

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