Westminster terror attack ...

Four people, including an armed police officer, have been killed after a knifeman brought terror to the heart of Westminster.

 The attacker, armed with two large knives, mowed down pedestrians with his car on Westminster Bridge, including schoolchildren, then rushed at the gates in front of the Houses of Parliament, stabbing the policeman before being shot dead by other officers.

 Eyewitnesses described scenes of terror when gunfire rang out as the attacker approached a second officer within yards of the Houses of Parliament.

 Paramedics fought to save the assailant’s life and that of his victim on the floor of the cobbled courtyard in front of Parliament with Foreign Office minister Tobias Ellwood among those who rushed to help.

  The knifeman drove a grey Hyundai i40 across Westminster Bridge -striking several pedestrians – before crashing it into railings then running through the gates of the Palace of Westminster.

 His attack left a trail of destruction as paramedics tended to victims on the bridge and at the gate.

 Scotland Yard’s top anti-terror officer Mark Rowley said the two other fatalities were on the bridge when the terrorist struck. At least 20 other people were injured.

 Mr Rowley told reporters outside New Scotland Yard, just yards from the scene of the attack: “This was a day we’ve planned for but hoped would never happen. Sadly it is now a reality.”

 The Met Police has confirmed they are treating the incident as a terrorist attack until they know otherwise.

 A counter-terrorism investigation is already under way, police said.

 Giving a statement outside Scotland Yard, police spokesman Commander BJ Harrington said: “A senior national coordinator has declared this a terrorist incident.

 “Although we remain open-minded to the motive, a counter-terrorism investigation is already under way led by the Met counter-terrorism command.

 “We received a number of different reports which included a body in the river, a car in collision with pedestrians and a man armed with a knife.

 “Officers were already in the location as part of routine policing but immediately additional officers were sent.”

 Witnesses have said they saw a man with a knife within the confines of the Palace and then heard gunfire and scenes of panic.

 An air ambulance was been sent to the scene and police are also in attendance.

 The sitting in the House of Commons has been suspended while police officers sealed off the area around the incident. Staff inside Parliament have also been told to stay inside their offices.

  Scotland Yard has confirmed it was called to a firearms incident on Westminster Bridge amid reports of several people injured.

 Armed police cleared the area around the incident and Parliament Square was closed to traffic.

 Prime Minister Theresa May was seen being ushered into a silver Jaguar car as what sounded like gunfire rang out at Parliament during the incident at around 2.45pm.

 Her official spokesman said: “The Prime Minister was brought back to Number 10 from Parliament. She is currently monitoring the situation.”

 The office of the Serjeant at Arms, who handles security in the House of Commons, said: “We are aware that there has been an incident that has taken place.

 “At this early stage, we cannot comment further.”

 Mayor of London Sadiq Khan said: “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 under way. My thoughts are with those affected and their families.

 “I would like to express my thanks to the police and emergency services who work so hard to keep us safe and show tremendous bravery in exceptionally difficult circumstances.

 Buckingham Palace declined to comment about its security arrangements in light of the terrorist incident and referred all inquiries to the Met Police.

 But with the Royal Standard flying above the palace – indicating the Queen was in residence – it was clear some precautions had been taken as the gates, patrolled by armed police, had been closed.

 Donald Trump has spoken to Mrs May about the attack, the President’s spokesman Sean Spicer said, adding: “We condemn’s today’s attack.”

 US Secretary of State Rex Tillerson said: “On behalf of the United States, I express my condolences to the victims and their families.

 “The American people send their thoughts and prayers to the people of the United Kingdom.

 “We condemn these horrific acts of violence, and whether they were carried out by troubled individuals or by terrorists, the victims know no difference.”

 Meanwhile the Scottish Parliament has suspended its independence referendum debate following the attack.

 Addressing the crowd, which included ministers, MPs, peers and tourists, from the pulpit a Met Police superintendent said it would take around 90 minutes to process everyone.

 Police said people would be assessed to see if they have any information.

 A prayer was then said for the victims of the attack./Agencies