A manhunt is under way to find the person behind Friday's Tube bombing
Police are 'chasing down suspects' and trawling CCTV after Parsons Green attack
Terror threat level raised to 'critical' - meaning an attack is expected 'imminently'
The station reopened in the early hours of Saturday
29 people have been treated in hospital - police say 'most' had 'flash burns'
The explosion on the District Line train is being treated as terrorism
Police say it was caused by an 'improvised explosive device'
Anyone with information, photos or video should call 0800 789 321
Frank Gardner
BBC Security Correspondent
Image source, Sylvain PennecThe indications are that the device at Parsons Green was designed to kill and maim a large number of people and that it failed to explode properly (similar to the failed 21/7 devices in 2005).
Explosives experts say it appears to have been a "deflagration" rather than a detonation, which would have killed everybody next to it.
The chair of the London Assembly has released a statement about the attack:
Quote MessageOur hearts go out to everyone injured in the Parsons Green explosion and once again we thank the emergency services for their prompt and professional care. These cowardly incidents only make us more determined to defy anyone who would attack us. Their attempts to disrupt our lives will not succeed and nothing they can do will sway us. We stand firm alongside all Londoners daily - and especially today.”
Jennette Arnold OBE AM, Chair of the London Assembly
Dominic Casciani
Home Affairs Correspondent
A device with a timer obviously suggests someone left it behind - although it is entirely possible the attacker intended to stay with the bomb until the end.
Specialist CCTV search officers will now be looking for who was carrying the distinctive Lidl freezer bag and its bulky contents on to the Tube.
The London Underground is smothered with CCTV - and there were five stations to the south of Parsons Green that could have been the entrance point for the attackers and the device.
Whoever carried the device would have been captured on scores of cameras during their journey.
Once the attacker has been spotted, the officers will then have to work out if they were alone and where they came from before they joined a train.
Image source, PA
Image source, ReutersNHS England has confirmed that 22 people are being treated in hospital following the explosion.
Paramedics took 18 patients to hospital while four "self-presented".
The hospitals treating victims are: Imperial, Chelsea and Westminster, Guy's and St Thomas' and the Central London Community Healthcare Urgent Care Centre in Parsons Green.
The Metropolitan Police would not be drawn on Donald Trump's comments, external that the "demented and sick people were in the sights of Scotland Yard".
"It is not something we would comment on," a spokeswoman said.
Image source, AFPArmed police entered a nursery school close to Parsons Green station this morning following the explosion on a Tube train.
Children and parents were arriving at Zebedee Nursery when police were called to the incident.
Parents at the school said children were kept inside by armed officers.
The principal Susan Gahan told BBC News: "The police were amazing, we didn't have many children as parents couldn't get to us
"Everything was very calm and organised," she said.
Assistant Commissioner Mark Rowley, from the Metropolitan Police, said the blast was caused by an improvised device.
Read MoreAssistant Commissioner Rowley says Londoners can expect to see an enhanced police presence across transport systems today for reassurance.
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
Dominic Casciani
Home Affairs Correspondent
BBC understands the device that detonated on the Tube at Parsons Green had a timer.
If you have anything on your phone that could help the police operation, you can upload the material via this webpage. Public Appeal For Photos/Videos, external
Mr Rowley said it was understood that "most" of the 18 injured and taken to hospital are suffering from "flash burns".
Met Police Assistant Commissioner Mark Rowley said the Parsons Green explosion was caused by the detonation of an improvised explosive device.
Rachel Green, 18, was working in a coffee shop outside Parsons Green station when she heard the explosion.
"We heard a bang and then we were realised there were many distressed people leaving the station. We went to console them," she tells the BBC.
"There were over 100 – women coming out without shoes, battered and bruised, and they’d left their handbags behind.
"There was talk of a fire. Two people came in to the shop with their clothes burnt off, who said they saw a fire coming towards them.
"There were mothers with babies, it was the school rush time. I’m really shocked – this is a quiet family-friendly area.”
Commuter Aaron Butterfield was trying to get into the station to get to work.
"People weren't even running, they were literally crawling over one another and just fleeing I guess," he said.
The production manager said police had told him there had been an explosion and "someone was running around with a knife".
"Then we have just been told there's another explosive device.
"It's been really frightening and very confusing especially as no-one really knows what's going on," he added.
Quote MessageWe got on the train at Parsons Green, then I heard lots of screams and people saying ‘run, run’. We got out of the train and then there was a human stampede, down the stairs. There were people lying underneath getting crushed. I wedged myself in next to a railing, I put myself in the foetal position. I kept thinking, ‘I’ll be ok, I’ll be ok.’ There was a pregnant woman underneath me, and I was trying really hard not to crush her. I can’t think how many people were underneath me in the crush. The fire brigade was telling us to get back on the platform, but no-one was. There was a full Tube worth of people on the steps – hundreds of people. I saw a lady with water being poured over the face and hands who I think had been burnt in the explosion. The injuries from the stampede seemed the worst. I’m outside now, there are women crying and people sitting on the floor.”
Emma Stevie, 27, Witness at Parsons Green
Witness describes 'smell of burning' at Parsons Green
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.