LONDON — Fresh details emerged Monday about the actions of a Polish kitchen worker who engaged in one-to-one combat with the London Bridge attacker.

The attacker, Usman Khan, 28, killed two Cambridge graduates and stabbed at least three others on Friday before he was chased down by bystanders and shot dead by police.

Speaking to the BBC, Toby Williamson, chief executive of Fishmongers’ Hall, explained how his staff and guests confronted and fought Khan.

It all began shortly before 2 p.m. Friday at Fishmongers’ Hall, next to London Bridge, where Cambridge University was hosting a fifth anniversary event for Learning Together, a prison-based education program.

Khan was attending the event. According to the Guardian, he sat through sessions early in the day. He was seen going to the bathroom carrying a bag, the paper said, and when he returned, he had knives strapped to his wrists.

Williamson described how an employee, whom he identified only as Lukasz, had been cleaning glasses in the basement of the building when he heard screams.

He ran up to the first floor of the hall, where he came across “blood, screaming and chaos,” Williamson said. Lukasz grabbed a pole off the wall (initial reports said it was a narwhal tusk) and charged at the assailant but failed to make much impact. Police would later say that the assailant was wearing a fake explosives vest.

“At that point, he’s got about a minute of one-on-one straight combat. This guy we know now by the name of Khan, he works his way up Lukasz’s pole, slashing with this knife and [Lukasz] takes five wounds to his left side and is going to lose some strength on that side,” Williamson said.

Lukasz’s actions allowed time for others in the room to escape to other parts of the building, Williamson said.

Two men attending the charity event then joined the fight, according to Williamson. Khan ran down the main staircase and tried to flee the building. A man Williamson identified only as Andy, a former Ministry of Defense police officer, was stabbed in the chest before he reluctantly opened the door, Williamson said.

People piled out of the building in pursuit of Khan, with Lukasz leading the charge, everyone headed in the direction of London Bridge.

“The first one after him is Lukasz,” Williamson said. He was shouting at the public to “get out of the way” and “get back.”

“But I tell you what, members of the public just don’t do that nowadays. They do what they needed to do,” Williamson added. Amateur footage circulated widely on social media showed a man with a fire extinguisher and another with a narwhal tusk wrestling Khan to the ground.

Williamson said that man widely lauded as a hero was unlikely to step forward.

“You’re not going to see Lukasz,” he told Sky News, noting that “he’s too modest.” On Tuesday night, Lukasz issued a statement, via the police, saying he had been released from the hospital. He also cleared up the confusion over the narwhal tusk, saying that he had used a pole to take on the assailant, while someone else used the tusk.

“When the attack happened, I acted instinctively. I am now coming to terms with the whole traumatic incident and would like the space to do this in privacy, with the support of my family,” he said in the statement.

On Monday, a vigil was held in London to honor Saskia Jones, 23, and Jack Merritt, 25, who were stabbed to death.

Mayor Sadiq Khan said the “best way to defeat this hatred” was to focus on the “values that bind us” and to take hope from the heroism of “ordinary Londoners” who “ran towards danger.”

He also said that people could draw “inspiration from the lives of Jack and Saskia, who from an early age chose to dedicate themselves to helping others.”

Prime Minister Boris Johnson and Labour leader Jeremy Corbyn were among those who attended the vigil.

On Sunday, the two political leaders clashed over who was to blame for the early release of Khan, who served less than half of a 16-year sentence.

Merritt’s family has said that their son wouldn’t want the tragedy to be a pretext for introducing more draconian sentences.

David Merritt, Jack’s father, tweeted the front pages of some of Monday’s newspapers that claimed there was a “new blitz on freed jihadis.”

“Don’t use my son’s death, and his and his colleague’s photos - to promote your vile propaganda. Jack stood against everything you stand for - hatred, division, ignorance,” he wrote.

This post has been updated.