A source inside the building said a car crashed into the Parliament gates and a man ran through security with a knife - before being shot by police
Five people have died and the British Parliament has been locked-down after a terrorist attack in the Westminster area of London.
Metropolitan Police Assistant Commissioner Mark Rowley confirmed that a police officer and the attacker have died in the attack.
Two others were killed when the attacker ploughed his car into pedestrians on the pavement of Westminster Bridge.
He said at least 20 people were injured in the attack.
The police officer who died was named by Scotland Yard as Keith Palmer, a 48-year-old husband and father.
The attacker drove over between ten and 12 people on Westminster Bridge before crashing his car into a railing near New Palace Yard - and launching an assault on police officers outside the parliament building.
A source inside the grounds told Newstalk that, after getting out of the car, the man ran through security and stabbed a police officer - before being shot three times by plain clothes police.
Witnesses described hearing people screaming and seeing bodies scatter as the car mounted the pavement just in front of the Houses of Parliament.
Cmdr Harrington “The events near Parliament Square #Westminster has been declared a terrorist incident”— Metropolitan Police (@metpoliceuk) March 22, 2017
“The attack started when a car was driven over Westminster Bridge, hitting and injuring a number of members of the public - also including three police officers on their way back from a commendation ceremony,” said Assistant Commissioner Rowley.
“Sadly I can confirm that now four people have died, that includes the police officer who was protecting parliament and one man we believe to be the attacker who was shot by a police firearms officer. The officer’s family have been made aware. At least 20 people have been injured.”
“As part of long established and well rehearsed plans, Parliament has been locked down and the Met responded in line with our plans for a marauding terrorist attack. That response included uniformed and specialist firearms officers.”
Assistant Commissioner Rowley said police currently believe there was only one attacker adding, “I’m sure the public will understand us taking every precaution in locking down and searching the area as thoroughly and exhaustively as possible.”
He moved to reassure the public, saying that extra police officers, both armed and unarmed, would be patrolling the streets in the coming days.
“We’re satisfied at this stage that there looks to be only one attacker but it would be foolish to be over-confident so early on,” he said.
The incident occurred on the first anniversary of the Brussels attacks that killed 32 people and injured more than 320.
Addressing the media just after 4:30pm this afternoon, Commander BJ Harrington, senior officer at Scotland Yard said there have been “a number of casualties including police officers.”
“There is an ongoing investigation being led by the counter-terrorism command and we would ask anybody who has images or film of the incident to pass those to the police,” he said.
“Our response will be ongoing for some time and it is important that we gather all possible information and evidence.”
He said that officers had received a number of different reports which "included a person in the river, a car in collision with pedestrians and a man armed with a knife."
The London Ambulance Service said they have treated "at least 10 people" on the bridge:
Three police officers are said to be among those injured in the attack.
In a statement the Mayor of London Sadiq Khan said police are "dealing with the incident" adding that his "thoughts are with those affected and their families:"
Approximately a dozen people were injured on Westminster Bridge after a black SUV appeared to deliberately run down pedestrians on its way towards Parliament.
The French prime minister has confirmed that three French teenage students had also been hurt in the incident.
Bernard Cazeneuve offered France's "solidarity with our hard-hit British friends" and offered his support to the "wounded French students, their families and their comrades."
Solidarité avec nos amis britanniques terriblement frappés, plein soutien aux élèves français blessés, à leurs familles et leurs camarades.— Bernard Cazeneuve (@BCazeneuve) March 22, 2017
A junior doctor at St Thomas' Hospital said that a number of the people on the bridge had received "catastrophic" injuries.
The London Underground station of Westminster was closed because of the incident.
An air ambulance landed in Parliament Square minutes after the incidents and medics treated two people at the scene.
Foreign Office minister and former army office Tobias Ellwood gave mouth-to-mouth resuscitation to one of the police officers injured in the knife attack in New Palace Yard, the cobbled courtyard in front of Parliament.
The British Parliament was immediately shut down and Prime Minister Theresa May was bundled into a car as officers searched the building, evacuating floors one by one.
However, the evacuation was delayed after a suspicious package was found in a vehicle and the bomb squad were called in to deal with it.
Staff in other buildings around Westminster were being asked by police to stay inside their offices.
Nearly 1,000 people have now been moved from Parliament to Westminster Abbey.
Reverend John Hall, the Dean of Westminster tweeted his welcome to Members of Parliament, staff and others:
Mrs May was escorted out of the building by a plain clothes policeman and put in a car.
She was briefed in Downing Street and the British government have called a special COBRA (Cabinet Office Briefing Room A) in Whitehall for tonight.
A Downing Street spokesperson said Mrs May will convene an emergency security committee meeting this evening.
Prime Minister Theresa May condemned the "sick and depraved terrorist attack" and paid tribute to the emergency services involved in the incident.
"On behalf of the whole country, I want to pay tribute to all our emergency services for the work they have been doing to reassure the public and bring security back to the streets of our capital city."
"The location of this attack was no accident," she said. "The terrorist chose to strike at the heart of our capital city, where people of all nationalities, religions and cultures come together."
"For those of us who were in Parliament at the time of this attack, these events provide a particular reminder of the exceptional bravery of our police and security services who risk their lives to keep us safe.
"Once again today, these exceptional men and women ran towards the danger, even as they encouraged others to move the other way."
Mrs May also said Parliament would meet in the morning "as normal".
Mayor of London Sadiq Khan says he has spoken to senior police officers.
Additional officers will be on duty tonight, he said. London remains one of the safest cities in the world, he added.
Londoners will never be cowed by terrorism. pic.twitter.com/SidIuIztvu— Mayor of London (@MayorofLondon) March 22, 2017
In Washington US President Donald Trump has condemned the London attacks.
White House spokesperson Sean Spicer said the president has already spoken to Theresa May by phone and has been receiving constant intelligence briefings on the situation:
The US Secretary of State Rex Tillerman also issued a statement expressing his condolences to the victims and their families on behalf of the American people.
“The American people send their thoughts and prayers to the people of the United Kingdom,” he said. “We condemn these horrific acts of violence, and whether they were carried out by troubled individuals or terrorists, the victims know no difference.”
Press Association reporter Laura Harding, who was in Westminster at the time of the incident, said a number of groups were evacuated into the building’s central lobby:
Hundreds of people, including schoolchildren, packed into central lobby in parliament after reports of firearms incident outside.— Laura Harding (@LauraSHarding) March 22, 2017
Schoolchildren in high vis jackets being led in song by their teachers. Security yelling at people for taking photos.— Laura Harding (@LauraSHarding) March 22, 2017
The children (about 40 in total) are now being moved out of the lobby.— Laura Harding (@LauraSHarding) March 22, 2017
One witness to the attack, Rick Longley said: "We were just walking up to the (tube) station and there was a loud bang and a guy, someone, crashed a car and took some pedestrians out.”
"They were just laying there and then the whole crowd just surged around the corner by the gates just opposite Big Ben,” he said.
"A guy came past my right shoulder with a big knife and just started plunging it into the policeman.
"I have never seen anything like that. I just can't believe what I just saw."
Other witnesses described seeing a middle-aged man carrying a knife and running.
Jayne Wilkinson said: "We were taking photos of Big Ben and we saw all the people running towards us, and then there was an Asian guy in about his 40s carrying a knife about seven or eight inches long.
"And then there were three shots fired, and then we crossed the road and looked over. The man was on the floor with blood.
"He had a lightweight jacket on, dark trousers and a shirt.
"He was running through those gates, towards Parliament, and the police were chasing him."
A woman in Parliament Square at the time of the shooting said: "We literally just heard shots and then saw people running, and we went to have a look.
"I saw a body, they were working on the floor. They were just inside the gates.
"He had one gunshot wound to the right side of his chest. I don't know if he was dead or alive, but people were working on him."
The London Eye tourist attraction, just across the Thames from Parliament, said it was on lockdown following the attack and sightseers were being held inside the viewing pods.
A spokesman said: "At present we are holding all of our guests within our attractions as per tried and tested security procedures.”
In a statement this evening, the Minister for Foreign Affairs, Charlie Flanagan "unreservedly condemned" the attack.
"I deplore the loss of life and note that the casualties include a police officer killed in the line of duty," he said. "I wish to extend my condolences and on behalf of my Government, my support to the people of London and the UK.
"Terror and violence will never triumph over democracy.
He said the department currently has no reason to believe that any Irish citizens "have been affected or are persons over whom there are concerns."
"Anyone concerned about family members in London should contact my Department on 01 408 2000, or the Embassy in London on 0044 207 235 2171,” he said.
Additional reporting from IRN ...