Transcript for London police investigate explosion on train

This device in flames on a subway train. Counterterror police helping people evacuate. A manhunt is under way. George is right there for us in London. Good morning, George. Good morning, robin. Just after I landed around 8:20 A.M., the height of rush hour here in London the first calls came about this explosion. An ied, improvised explosive device at the parsons green station, a suburb of London here. A lot of commotion there at that station. Right now we know that 18 people have been taken to hospitals. No life-threatening injuries as far as we know. Very serious incident. As you said the prime minister called an emergency meeting right now. I've been in touch with 10 downing street. That meeting will happen within the next hour. They are treating this as a terror incident right now and there is a live manhunt going on across London right now for whoever may have done this. Now, president trump is already up and tweeting about this and said there's another attack in London by a loser 2ri69. These are sick and demented people in the sights of Scotland yard. Must be proactive. I have to say we have not confirmed they knowho did this but as I said they are actively searching now for whoever may have done this right here in London. I want to go on the scene now to Ian Pannell at the parsons green station. Reporter: George, it's incredible. Here we are reporting on yet another terrorist attack in the uk. This is the sixth attack that's taken place here underlying the level of threat that people in the uk are now having to live with. Not just here but also in continental Europe so the subway station is just down the road probably about 300 or 400 yards. This is parsons green. A genteel very upper class part of London. The kind of area where people who have lots of money tend to live. The time that it took place, there were people taking children to school. The subway was packed then disaster happened. Two passengers fleeing in panic this morning. Still shocked. I'm shaking but just trying to calm down. Reporter: After this bucket exploded in the heart of London on a packed train. Emergency responders rushed to the parsons green subway station where witnesses say people were crying, screaming, knocking each other over trying to get out. I just ran as well. Just hordes of people and the stampede started running towards me within about five seconds. It was just apparent it was -- yeah, not a safe place to be and then as the doors opened people were running down the platform, down the stairs. Reporter: Flames from the bucket causing numerous burns to passengers. The smell of like plastic burning, like clothing. Reporter: Law enforcement spotted racing down the tracks as rescue worked for hours evacuating people from the train. This video shows the bucket in flames after the train emptied. The terror threat in the uk has been at its highest possible level after several terrorist attacks in recent months. In June eight people were killed and 48 injured after an attack on London bridge and the borough market. Oh, my god. Reporter: 22 concertgoers murdered at this Ariana grande concert in Manchester and five killed in March after a vehicle attack at Westminster. Well, as we said, this is the sixth terrorist incident. There is a live investigation under way and what we know at the moment is that we don't think they've apprehended a suspect and that this was an improvised explosive device. One small piece of good news, it wasn't as bad as people thought it could have been and so the injuries weren't so bad. The police are coming through so we need to move now.

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