Young British boxers have told of their shock and horror after witnessing the violent attack outside the Palace of Westminster.
The group from Great British Boxers were leaving a press conference ahead of the World Series Boxing event against Italy in York Hall on Thursday when they came face to face with the alleged assailant.
Frazer Clarke, 25, from Burton-on-Trent, was walking to the coach with his teammates when he witnessed the horror.
He told the Press Association: "We heard a loud bang and screaming and then I noticed some smoke. I thought it was a car crash.
"I looked towards the front gate and people were running, a police officer and a fellow coming to the gate with two knives.
"He was stabbing the police officer with the knives.
"He was wearing black tracksuit bottoms, a black of grey top and what looked like work boots.
"The police officer was stumbling and fell on the floor.
"Another police officer walked toward the guy with the knives and shot him twice. I didn't think they were proper bullets, they seemed like rubber bullets.
"Then people started shouting at us to get inside.
"Time stood still and I was shocked. The first thing I thought was this was a terrorist attack.
"It all happened so fast."
Pat McCormack, 21, from Washington in Tyne-on-Wear added: "I saw him stabbing the officer in the back of the head and the back of the neck.
"He was running away but then he collapsed.
"I wasn't scared.
"I just couldn't believe what was happening."
The group of boxers were among the hundreds of people being held in the lobby during the security alert.
Schoolchildren were led in song and shown pictures of the House of Commons as they were detained in the lobby before being taken away.
Two groups of young children, one in blue high vis jackets and one in yellow, sat on the floor beneath the huge central chandelier as they sang songs with their teachers while armed officers guarded the doors to both chambers.
Later members of Parliament's education team could be heard teaching them about the Queen's Speech and showing them photos of where the Prime Minister sits.
Groups of tourists and staff sat in small groups on the floor of the grand lobby while plug sockets to charge mobile phones became increasingly in demand and cups of water were passed around.
Screens over the information desk read: "Security incident. Buildings are locked down. Remain in your current location. Do not move around the building."
People being held in the central lobby have been moved into Westminster Hall, where journalists with offices in parliament, and Health Secretary Jeremy Hunt, are among those waiting.
Former Labour leader Ed Miliband was seen being led through the hall.
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