LONDON (AP) — British Prime Minister Boris Johnson and main opposition Labour Party leader Jeremy Corbyn paused Monday to honor the two people killed in the London Bridge attack, then went back to trading blame for the security failings that allowed a man who had been jailed for terrorist crimes to go on a violent rampage in the heart of London.

Usman Khan stabbed two people to death and injured three others Friday before being shot and killed by police on the bridge. Two of the injured remain hospitalized in stable condition.

Politicians, who are campaigning ahead of Britain’s Dec. 12 election, immediately sought to deflect blame for the first fatal attack in London since 2017. Johnson accused Labour of being soft on terrorism and vowed to end the early release of inmates convicted of terrorist crimes. He said it was “repulsive that individuals as dangerous as this man” could be freed.

Corbyn blamed years of cuts to the police, prison and parole services by Conservative governments left the system unable to monitor offenders.

He said the tragedy raised “enormous questions” about how the attacker’s state of mind had been evaluated, and “what supervision and monitoring he was under” after leaving prison.

Political dignitaries, city officials, friends of the victims and Londoners who had never met them attended a vigil outside London’s medieval Guildhall to remember Jack Merritt and Saskia Jones, who died in the attack, and to honor members of the emergency services and bystanders who fought the attacker with fists, fire extinguishers and even a narwhal tusk.

Mayor Sadiq Khan said people should “take hope from the heroism of ordinary Londoners and emergency services who ran toward danger, risking their lives to help people they didn’t even know.”

Former University of Cambridge students Jones, 23, and Merritt, 25, were fatally stabbed by the 28-year-old attacker at an event run by the Cambridge-based prisoner rehabilitation program Learning Together. Merritt worked for the program and Jones was a volunteer.

Usman Khan was attending the event at London’s Fishmongers’ Hall and had returned for the afternoon session when he started stabbing people. Police believe he acted alone.

He was pursued onto London Bridge and restrained by staff from the venue and others from the conference, including former inmates. Police opened fire after he flashed what looked like a suicide vest. It turned out to be fake.

Toby Williamson, chief executive of Fishmongers’ Hall, paid tribute to staff who tried to help the wounded and fight off the attacker. Williamson said one staffer, a kitchen worker he identified as Lukasz, pulled a 5-foot narwhal tusk from the wall and charged at Khan, allowing others to escape.