At least four people were killed as a result of the March 22 Westminster “terror attack,” police confirmed in a press conference. The alleged attacker was among those killed. Twenty people were injured, police said.

The police responded to reports of a security incident when a vehicle drove into pedestrians on Westminster Bridge. A police officer was also stabbed near the Houses of Parliament.

The events were being treated as a terrorist incident by police. Video uploaded to Twitter showed people on the bridge being helped up by other members of the public.

The parliament building was placed on lockdown, during which time MPs shared photos and video from inside.