Stunning video has shown how the London Bridge knife attack was stopped by a chef using a narwhal's tusk as a weapon, while another man - a convicted murderer on day release from prison - sprayed a fire extinguisher.
A group of bystanders tackled a man who stabbed multiple people on London Bridge, killing two and injuring at least three others.
The attacker, Usman Khan, was apparently attending the event and had returned for the afternoon session when he started stabbing people.
The London Bridge stabbing suspect wanted to carry out "Mumbai-style attacks" in the United Kingdom but had no trouble taking the country's benefits, according to reports.
At the time of the attack, Khan had participated in a conference organised by the University of Cambridge on the reintegration of prisoners, in a building on the north end of London Bridge.
The medical director for the NHS in London, Dr Vin Diwakar, said on Sunday that one of the three people injured in the attack had been allowed to return home while the other two remain in a stable condition in hospital.
"We know Jack would not want this awful, isolated incident to be used as a pretext by the government for introducing even more draconian sentences on prisoners, or for detaining people in prison for longer than necessary", his family said.
Khan was believed to have lived in the area after his release from prison.
Questions over rehabilitation Britain's Parole Board, meanwhile, said it had no role to play in Khan's freedom as he was released automatically on license, as required by United Kingdom law.
"We don't think that it is the case that they should all necessarily be released, we think for some offences they should be imprisoned for life, and we also think that terrorist offenders should serve their full sentence".
"You've got a community which is coming together in a brilliant way and straight out of the door the Prime Minister's trying to make it an election issue - I just think it's pretty distasteful".
After searching on Saturday two properties in central England believed to be linked to Khan, police have said they believe he was acting alone and are not seeking anybody else.
Merritt was reportedly a Cambridge University graduate who was working for its "Learning Together" initiative run by the Department of Criminology to promote prison-based education.
"We're supporting the police through this very hard investigation".
A British Transport Police officer in a suit and tie who also intervened was later seen carrying a large knife away.
But was released in December 2018 - subject to conditions.
Inmates are usually released half-way through this type of determinate sentence - and time spent in custody before trial may have been taken into account.
Some people at the event, including prison staff and former prisoners, put their lives in danger to restrain the attacker until police arrived, officials said.
The Parole Board said it had no involvement in his release and that it appeared to have happened automatically as required by law.
British Prime Minister Boris Johnson said on Sunday he would strengthen prison sentences, vowing to boost security after an attack in London by a man jailed for terrorism who had been released early.