Four civilians and a policeman have died and at least 40 others were injured near the British Parliament in London on Wednesday after gunshots were heard in the vicinity. The assailant, who has been shot dead, is believed to have mowed down a number of people on Westminster Bridge, which he drove down before heading to the Parliament, BBC reported.

UK’s Metropolitan Police said they were treating the attack as a “terrorist incident” until proven otherwise. They had earlier said they would investigate the shooting as one involving firearms.

The officer who died was stabbed by the assailant. Those on the bridge have suffered “catastrophic injuries”.

The Metropolitan Police Commander BJ Harrington said, “A full counter-terrorism investigation is under way...We cannot confirm numbers or the nature of these injuries at this stage.” Security has been heightened and additional officers have been deployed across London.

Eyewitnesses said there were at least a dozen people lying on the ground, bleeding heavily on the bridge. An air ambulance is treating the injured and working to move the casualties. The London Ambulance Service has confirmed that they had treated at least ten patients on Westminster Bridge so far. One woman hit by the car later died, the BBC reported.

Officials said the Westminster underground station had been shut. There are plans to declare a London-wide emergency as a precaution, according to The Guardian.

A woman was rescued alive from the Thames river, but with serious injuries. The Port of London Authority said she had either fallen in or jumped from the bridge to escape the attacker.

The House was under lockdown as officials investigated the incidents. The House of Commons, which was in session when the gunshots were heard, has been suspended. Lawmakers have been asked to stay put. Prime Minister Theresa May will hold an emergency security meeting.

Journalist Quentin Letts, who was in the neighbourhood, said he saw Parliamentary security shoot a man who stabbed a policeman. The policeman later succumbed to his injuries.

“There was a loud bang. Screams. Commotion. Then the sound of gunshots. Armed police everywhere,” The Independent’s political correspondent Tom Peck posted on Twitter.

Source: Reuters