"We are treating it as a terrorist incident until we know otherwise," Metropolitan Police tweeted.
Incident in #Westminster: We are treating this as a terrorist incident until we know otherwise— Metropolitan Police (@metpoliceuk) March 22, 2017
According to preliminary data, an unidentified attacker mowed down several pedestrians on Westminster bridge and then crashed his car into a Westminster Palace rail.
Around the same time, a knife-wielding man attacked a police officer on duty outside the Parliament. Police opened fire on the attacker.
"Someone rushed through, attacked a policeman... he appeared to be carrying a knife. We heard lots of gunfire" witness tells Sky News pic.twitter.com/3tMbYIoByH— Sky News (@SkyNews) March 22, 2017
Sky News reported, citing its source in law enforcement agencies, that the attacker was the same in both incidents, according to preliminary data.
Reuters photo correspondent reported from the scene on a "dozen" victims.