LONDON (AP) — The head of counterterrorism at London’s Metropolitan Police, says four people have died in the terror incident in London, including an attacker and a police officer.

Mark Rowley says some 20 people have been wounded and Parliament was locked down. A search is underway to make certain no other attackers are in the area — though police believe there was only one attacker.

Rowley said the dead policeman was one of the armed officers who guard Parliament. The other victims were on Westminster Bridge.

Rowley says “We are satisfied at this stage that it looks like there was only one attacker. But it would be foolish to be overconfident early on.”

The White House is condemning the attacks in London involving a car rampage and knife attack. President Donald Trump is said to be monitoring developments.

Spokesman Sean Spicer said Wednesday, Trump spoke with British Prime Minister Theresa May and said that the White House applauds “the quick response of British police and first responders” and condemns the attacks.