According to police, they received the first call about the attack at Fishmongers' Hall around 2:00 p.m. local time. Khan reportedly started attacking people there, and one of them died inside of the hall, according to The Times. Police reported the attacker exited the Hall and continued to attack others.
At the London Bridge, members of the public stopped Khan. According to videos posted on social media, people approached Khan armed with the fire extinguisher and the narwhal tusk and forced him to lie on the ground, after which a third person removed his knife. According to these videos and NPR, the police then surrounded the attacker aiming at him with their guns, moved a last bystander out of the way, and shot Khan.
The University of Cambridge had been hosting a program about criminal rehabilitation at Fishmongers' Hall called "Learning Together". According to a Twitter post by Amy Cook, director of the Learning Together event, the five-foot (one and two thirds meters) marine mammal tusk came from the wall in Fishmongers' Hall. Łukasz, who reportedly works at Fishmongers' Hall as a chef, having thus armed himself, participated in the chase and sustained a stabbing injury to his hand before the police arrived. Broadcaster Piers Morgan commented, "The guy with the whale tusk is a Polish chef named Luckasz. Worth noting this for the next time someone says, 'we've let too many Eastern Europeans into this country'."
Police also said Khan had appeared to be wearing a suicide vest, though it was later found to be a harmless fake.
One of the men who held Khan down was James Ford, 42, a convicted murderer approaching the end of his sentence at an open prison. Another was tour manager Thomas Gray, 24, who cited only his experience with the sport of rugby: "'one in, all in'. I did what any Londoner would do and tried to put a stop to it."
"I am in awe of the people who ran towards danger to keep us all safe" tweeted Mayor of London Sadiq Khan (no relation). "The bravery of the emergency services and ordinary Londoners is incredible."
Khan was convicted of terrorism years ago for his participation in a London Stock Exchange bomb plan and served eight years of a sixteen-year sentence. He was released in 2018 and has been out on license, also called parole, and living in Staffordshire.
Lucy Fischer of The Times told NPR, "[Khan] had been released a year ago on the provision that he had agreed to wear an electronic tag, submit to curfews and restrictions to his movements".
"In the US there is a phenomenon 'suicide by cop'", Birmingham City University criminology professor David Wilson told the press. "[I]ncreasingly what we are seeing is some attackers wear pretend suicide vests as they prefer martyrdom than getting a sentence. I wonder if what we are seeing is another version of suicide by cop."