The man who killed three people outside the Houses of Parliament in London was British-born and had already been investigated by domestic intelligence services some years ago, Prime Minister Theresa May said Thursday.
In a statement to the House of Commons, May said that the man, who has still not been named, had been deemed a “peripheral figure.”
The police’s “working assumption” is that the attack was inspired by “Islamist terrorism” and the so-called Islamic State has said one of its “soldiers” was responsible for the attack, according to the BBC.
May’s admission highlights the problem facing the security services, which have only enough resources to monitor what they consider to be the most direct threats.
The attacker’s identity is being withheld while police continue the search for possible accomplices. English police raided six addresses in London and the U.K.’s second city Birmingham last night and made eight arrests, the BBC said.
The government quarter of Westminster its slowly returning to normal Wednesday after being in various degree of lockdown since the attack.
The attack, which came on the anniversary of terrorist outrages in Brussels last year, was the worst in Britain since a coordinated bombing of buses and subway trains in 2005. In that case too, the attackers had been British-born.