A witness to the Parsons Green bombing told the Old Bailey how his head was "engulfed in flames" during the attack.
Stephen Nash was on the District Line underground train on 15 September 2017 when the device went off.
CCTV allegedly shows Ahmed Hassan – who prosecutors said built the bomb and set the timer – leaving the train one stop earlier at Putney Bridge station, having left a bag behind.
He denies attempted murder and causing an explosion likely to endanger life,
The CCTV footage then showed the moment an orange fireball filled the carriage.
Prosecutor Alison Morgan has said experts concluded it was simply "luck" that the bomb did not fully detonate.
Mr Hassan was arrested at the Port of Dover the day after the attack.
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Mr Nash told the court he was was reading a newspaper, "oblivious" to what was going on, when the explosion happened.
He said: "At Parsons Green there was a loud bang. There was a blinding flash to my left and I was engulfed in flames."
He described an "intense heat", before adding: "I thought I had lost my ears. I thought my head was on fire."
Mr Nash said he was knocked out, and when he woke up a few seconds later, he was the last person on the train.
"I called out to the Tube," he said. "Just as I got to the doors, the doors started to close.
"It was a little bit scary and I called out on to the platform."
'Slow motion'
Mr Nash was among a number of witnesses giving evidence at the trial.
The court heard that many of the 93 people caught in the bombing suffered burns or were crushed in the stampede to get out.
Retired counter-terrorism officer Alex Beavan had boarded the train at Wimbledon and was standing near the doors when the bomb went off.
"I heard a huge popping sound," he said. "Looking towards the direction of the sound, I saw a rolling fireball coming over the ceiling at the back of the train.
"I saw the rolling fireball, wall to wall, slowly coming up the ceiling."
He added: "Everything goes in slow motion. There was chaos and I was thinking there is going to be a second attack, so I ran across the platform."
Aimee Colville, who got on the train at Parsons Green moments before the explosion, said she saw a "wall of glass" and flames coming towards her.
She said: "That morning I had curled my hair and I had put hairspray in my hair, so when the flames came over me my hair immediately caught fire."
Lucinda Glazebrook, who also boarded the train at Parsons Green, told the court she felt the heat from the fireball on her face.
"I kept touching my face and feeling the back of my hair and my hair was coming out in chunks," she said.
'Wall of faces'
An army officer travelling on the train turned towards the explosion because of his "instinct" and training.
Craig Palmer told the court that he wanted to know what had happened so began walking towards where the device had partly detonated.
He said: "I had a seen the wall of faces in terror who rushed past me.
"I could see something in the corner of the train, it was burning.
He added: "There was smoke billowing out of it and the carriage was filling up with grey smoke.
"I could smell, at that point, something I categorise as being explosives."
Mr Palmer said he expected to see a "suicide bomber" but he discovered the bomb, which he believed to be an "improvised explosive device".
He then took photos of it to share with special officers who arrived at the scene.
Journey before attack
A number of other videos allegedly showing Mr Hassan's movements on the day of the attack have been shown to the jury by prosecutors.
The first video is said by prosecutors to show him leaving his foster home in Sunbury, Surrey, carrying a plastic bag, which they told the court contained the device that exploded on the underground train.
A second then allegedly shows Mr Hassan catching a train to Wimbledon.
And CCTV from the platform allegedly shows him going into the station toilets – where prosecutors said he set the timer on the device – and emerging 13 minutes later carrying the bag and heading towards the District Line platforms.
Further footage was also shown, which prosecutors said showed Mr Hassan from a day before the attack going to two supermarkets – an Asda and an Aldi in Feltham – buying matches, batteries, a screw driver and screw driver bit sets, allegedly used to construct the device.
Jurors were also shown a replica of the home-made bomb without the explosive, which was held in a Lidl frozen goods bag and contained 2.2kg of shrapnel.
The court was told that Mr Hassan's fingerprints were found on the Tube carriage, on a white plastic bucket inside the bag, and on a pair of trousers covering the bucket.
His DNA was also found at the scene.
Giving evidence, explosives officer Andrew Gee said a test carried out to identify the explosive used was an "87% hit" for the chemical compound TATP.
'Trained to kill'
On Wednesday, the prosecution said that Mr Hassan had told Home Office officials, 20 months before the Parsons Green attack. that he had been "trained to kill"
Ms Morgan said he was interviewed in Croydon in January 2016 where he is alleged to have told them he had been taken by force by Isis (the Islamic State group), who had threatened to kill his uncle and brother if he resisted.
The court also heard he had arrived in Britain in the back of a lorry via the Channel Tunnel in October 2015.
He claimed asylum, and from 2016 lived with foster parents in Cavendish Road, Sunbury, but his asylum claim was still outstanding as he planned the attack.
The trial continues.
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