The alleged attacker in London was a "soldier" of the Islamic State in Iraq and Syria (ISIS), the terror group claimed Thursday.
Through its Aamaq news agency, ISIS said the assailant who carried out the "attack in front of the British parliament in London was a soldier of the Islamic State," The Associated Press reported.
The person "carried out the operation in response to calls for targeting citizens of the coalition," ISIS claimed.
The attack Wednesday left four people dead, including the alleged assailant and a police officer. Nearly 30 other people were treated in a hospital, The Guardian reported.
On Wednesday, the assailant drove a car into people on the Westminster Bridge in London and then crashed it outside parliament. The attacker then stabbed a police officer before being shot by armed police.
Prime Minister Theresa May said the attacker was born in the United Kingdom and had been investigated "some years ago." But she said the attacker was "not part of the current intelligence picture."
In a statement Thursday to parliament, May expressed strength.
"We are not afraid," she said. "And our resolve will never waiver in the face of terrorism."
President Trump on Wednesday night said he had spoken with May to offer his condolences.
"She is strong and doing very well," he tweeted.