UK Parliament attack: Four dead, 20 injured in 'terror incident'

A policeman was stabbed, an assailant was shot and 20 people injured in what police said they were treating as a terrorist incident near Britain's parliament.

Four people have died in the incident Sky News said on Twitter, citing unspecified sources. Earlier it was reported that a woman had died and other people were being treated for "catastrophic" injuries after the attack in Westminster in London.

An image of the man believed to be the suspect has surfaced on Twitter:

#BREAKING: image of the suspect in UK parliament terror attack pic.twitter.com/vfFyiPl0EW

— Amichai Stein (@AmichaiStein1) March 22, 2017

Reuters reporters inside parliament heard loud bangs and shortly afterwards a Reuters photographer said he saw at least a dozen people injured on Westminster Bridge, next to the parliament, in what police said they are treating as a terrorist incident.

The House of Commons, which was in session at the time, was immediately suspended and lawmakers were asked to stay inside.

I am inside the Chamber as Parliament is in lockdown following serious incident here. My Westminster staff member is also safe.

— Toby Perkins MP (@tobyperkinsmp) March 22, 2017

The leader of the House, David Lidington, said in the chamber that an assailant who stabbed a policeman had been shot by police. Officers - including firearms officers - remain on the scene and we are treating this as a terrorist incident until we know otherwise," London's Metropolitan Police said in a statement. 

Incredibly brave @metpoliceuk anti-terror officers co-ordinating a lockdown & evacuation after #ParliamentAttack pic.twitter.com/XFv6KoNpm4

— George Freeman MP (@Freeman_George) March 22, 2017

Prime Minister Theresa May was safe, a spokesman for her office said. He declined to say where May was when the attack took place.

On Twitter, Mayor of London, Sadiq Khan, issued a statement: “There has been a serious incident near to Parliament Square this afternoon which is being treated as a terrorist attack until the police know otherwise.

"I have spoken to the Acting Commissioner. The Metropolitan Police Service is dealing with the incident and an urgent investigation is underway. My thoughts are with those affected and their families.

Amid confusing scenes, it appeared the incident may have unfolded in several locations, including the busy bridge where tourists often congregate to take pictures of Big Ben and other attractions. The incident took place on the first anniversary of attacks on Brussels in Belgium."

The London Ambulance Service earlier said it had treated at least 10 people on Westminster Bridge. "We can confirm we have treated at least 10 patients on Westminster Bridge and have put a number of hospitals on alert as we continue to respond to this incident," said London Ambulance Service Deputy Director of Operations Pauline Cranmer in a statement.

Officers – including firearms officers - are on scene and dealing with the incident in #Westminster

— Metropolitan Police (@metpoliceuk) March 22, 2017

Air ambulance is seen landing at Parliament Square, Westminster  along with dozens of police cars:

Air ambulance just landed at Parliament Square, Westminster, dozens of police cars pic.twitter.com/TZVTO6IzDR

— Peter Yeung (@ptr_yeung) March 22, 2017

London police said they were called to a firearms incident on Westminster Bridge near the British parliament on Wednesday.

We were called at approx 2:40pm to reports of an incident at #Westminster Bridge. Being treated as a firearms incident - police on scene

— Metropolitan Police (@metpoliceuk) March 22, 2017

Video posted on Twitter shows multiple wounded on the bridge:

*Graphic* Video appears to show aftermath on #Westminster Bridge. Knifeman shot by armed police. #London pic.twitter.com/LqKLwvrKJb

— Connor Gillies (@ConnorGillies) March 22, 2017

Reporters inside parliament said a large number of armed police, some carrying shields, were pouring into the building. Britain is on its second-highest level of "severe" meaning an attack by militants is considered highly likely.

Westminster attack latest:
• 4 dead, including attacker
• at least 20 injured
• police believe only one attackerhttps://t.co/WG8yXWpPVV pic.twitter.com/U8yRbkfgmV

— BBC Breaking News (@BBCBreaking) March 22, 2017

CAR "OUT OF CONTROL"

"I just saw a car go out of control and just go into pedestrians on the bridge," eyewitness Bernadette Kerrigan told Sky News. She was on a tour bus on the bridge at the time. "As we were going across the bridge, we saw people lying on the floor, they were obviously injured. I saw about 10 people maybe. And then the emergency services started to arrive. Everyone was just running everywhere."

Officials said an assailant had stabbed a policeman and then been shot. Witness reports suggested the assailant and the stabbed policeman were the people seen lying on the ground outside the parliamentary building. The House of Commons, which was in session at the time, was immediately suspended and lawmakers were asked to stay inside.

Journalist Quentin Letts of the Daily Mail newspaper told LBC radio that he had witnessed the stabbing of the policeman and the shooting of the assailant from his office in the parliament building. "He (the assailant) ran in through the open gates ... He set about one of the policemen with what looked like a stick," Letts said. "The policeman fell over on the ground and it was quite horrible to watch and then having done that, he disengaged and ran towards the House of Commons entrance used by MPs (members of parliament) and got about 20 yards or so when two plain-clothed guys with guns shot him."

US President Donald Trump told reporters at the White House he had been briefed on events in London but gave no details. The incident took place on the first anniversary of attacks on Brussels in Belgium.

Britain is on its second-highest alert level of "severe" meaning an attack by militants is considered highly likely. In May 2013, two British Islamists stabbed to death soldier Lee Rigby on a street in southeast London. In July 2005, four British Islamists killed 52 commuters and themselves in suicide bombings on the British capital's transport system in what was London's worst peacetime attack.