The family of the Fishmongers’ Hall attacker, Usman Khan, have said they are “shocked and saddened” by the atrocity and “totally condemn” his actions.

In a short statement issued through the Metropolitan police, they expressed their condolences to the two victims who died and those who were injured in the violence on Friday.

“We are saddened and shocked by what Usman has done. We totally condemn his actions and we wish to express our condolences to the families of the victims that have died and wish a speedy recovery to all of the injured. We would like to request privacy for our family at this difficult time.”

Tributes were also paid to those who died by relatives and one of the people who fought off the attacker, sustaining injuries himself in the process. Łukasz, a porter at Fishmonger’s Hall, said: “I would like to express my condolences to the families who have lost precious loved ones. I would like to send my best wishes to them and everyone affected by this sad and pointless attack.”

Łukasz, who did not want to give his surname, described how he and others fought with Khan as he carried out the “unimaginable and tragic terrorist attack” last Friday. “I and several others tried to stop a man from attacking people inside the building. I did this using a pole I found. Someone else was holding a narwhal tusk,” he said, correcting reports that said he had wielded the tusk.

“The man attacked me, after which he left the building. A number of us followed him out but I stopped at the bollards of the bridge. I had been stabbed and was later taken to hospital to be treated. I am thankful that I have now been able to return home.”

“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.”

Earlier on Tuesday, the girlfriend of Jack Merritt, one of the two people who died in the attack, paid an emotional tribute to the “phenomenal” Cambridge graduate. Leanne O’Brien, who was comforted by family members as she wept during a vigil for Merritt in Cambridge on Monday, said her boyfriend had “opened so many doors for those that society turned their backs on”.

Merritt, 25, and Saskia Jones, 23, both Cambridge graduates, were stabbed to death by Khan, a convicted terrorist, during a prisoner rehabilitation event they were supporting at London’s Fishmonger’s Hall on Friday. Khan had been released early from prison last year on licence.

It comes after political leaders and criminal justice campaigners accused Boris Johnson of trying to politicise the terrorist attack.

O’Brien posted a link on her Facebook page on Monday evening to a piece written for the Guardian by Jack’s father, Dave, in which he said his son would be livid that the terror attack was being used to perpetuate an “agenda of hate”. Sharing the article, O’Brien said: “My love, you are phenomenal and have opened so many doors for those that society turned their backs on. Together, we will make a difference #learningtogether.”

The post prompted an outpouring of sympathy from her friends, who responded with messages of support.

Dave Merritt wrote in the Guardian that the death of his son, who worked as a coordinator for the Learning Together prison rehabilitation and education programme, run by the University of Cambridge’s Institute of Criminology, was being used to reinforce the world-view his son had fought against.

“Unlike many of us, Jack did not just go to work. He lived and breathed fire in his pursuit of a better world for all humanity, particularly those most in need,” he wrote.

“If Jack could comment on his death – and the tragic incident on Friday 29 November – he would be livid. We would see him ticking it over in his mind before a word was uttered between us. Jack would understand the political timing with visceral clarity.”

The family of Saskia Jones, also a volunteer on the programme, praised her for having a “great passion” for supporting victims of crime. “She was intent on living life to the full and had a wonderful thirst for knowledge, enabling her to be the best she could be,” a family statement said.

Saskia Jones. Photograph: HANDOUT/AFP via Getty Images

Johnson, Jeremy Corbyn and the mayor of London, Sadiq Khan, attended a vigil on Monday in memory of the victims at Guildhall Yard in central London, near the scene of the attack.

The attacker, who had been living in Stafford, was given permission to travel to London by the police and probation service. He was wearing a fake suicide vest and was shot dead by police on London Bridge after he was tackled by members of the public, including ex-prisoners from the conference.