The fatal stabbing of Conservative MP David Amess has been declared a terrorist incident, the Metropolitan Police has said.
The force said the investigation into the killing in Leigh-on-Sea, Essex, on Friday is being led by counter terrorism policing.
In a statement, the Metropolitan Police said senior national coordinator for counter terrorism policing, deputy assistant commissioner Dean Haydon, had formally declared the incident as terrorism.
The early investigation has revealed “a potential motivation linked to Islamist extremism”, the force said.
A 25-year-old man arrested at the scene on suspicion of murder is currently in custody at an Essex police station.
As part of the investigation, officers are currently carrying out searches at two addresses in the London area, the Met said.
The force believe the man acted alone and are not seeking anyone else in connection with the matter at this time but inquiries into the circumstances of the incident are continuing.
The Tory veteran, who had been an MP since 1983, was stabbed several times at Belfairs Methodist Church in Leigh-on-Sea near Southend at midday as he was meeting constituents.
Prime minister Boris Johnson led the tributes to one of the “kindest, nicest, most gentle people in politics”. The 69-year-old MP for Southend West was married with five children.
Sir David became the second British member of parliament in just over five years to be killed. In 2016, Labour MP Jo Cox was shot and stabbed in her constituency by a far-right supporter.
Tributes poured in for Sir David, who was first elected the MP for Basildon, before becoming the MP for Southend West in 1997.
Johnson said all our hearts are filled with “shock” and “sadness” as he reacted to the death.
The prime minister said Amess was killed after “almost 40 years of continuous service to the people of Essex and the whole of the United Kingdom”.
He added: “The reason people are so shocked and sad is above all he was one of the kindest, nicest, most gentle people in politics.
“He also had an outstanding record of passing laws to help the most vulnerable.”
Brendan Cox, the husband of the late Jo Cox who was murdered in her Batley constituency, said: “This brings everything back.”
“My thoughts and love are with David’s family,” he tweeted.
“They are all that matter now. This brings everything back. The pain, the loss, but also how much love the public gave us following the loss of Jo. I hope we can do the same for David now.”
Amess was knighted by Queen Elizabeth for his public service in 2015.
He never served in a ministerial role, focussing his efforts on local constituency matters. He was popular with politicians and known for his active contributions to debates – often about issues relating to his Essex constituency or animal rights.