British police named the man who stabbed two people to death in London on Friday in what the authorities called a terrorist attack as 28-year-old Usman Khan, who had been convicted of terrorism offenses and was released from prison last year, Reuters has reported.

“This individual was known to authorities, having been convicted in 2012 for terrorism offenses,” Britain’s top counter-terrorism police officer, Neil Basu, said in a statement.

“He was released from prison in December 2018 on license and clearly, a key line of enquiry now is to establish how he came to carry out this attack,” Basu said.

A person who is released on license is subject to conditions for the duration of their sentence after leaving prison. The Times newspaper reported that Khan had agreed to wear an electronic tag.

The attacker went on the rampage just before 2 p.m. In addition to the man and the woman who were killed, a man and two women were injured and remain in hospital. Khan was shot dead by officers after members of the public restrained him.

Police declared the attack a terrorist incident.