London attack: trail of destruction at capital's landmarks

Within seconds a spring day on London's landmark Westminster Bridge turned to horror when a car mowed down pedestrians before a police officer in the Houses of Parliament was fatally stabbed.

The incident, described by UK authorities as a terrorist attack, began about 2.30pm on Wednesday at the south end of the bridge when a driver in a Hyundai 4x4 drove on to the pavement and ploughed into the first pedestrians.

He continued along the pavement, hitting at least a dozen victims in total, two of which have been confirmed by the Metropolitan Police to have died, before crashing the vehicle into the railings of the Houses of Parliament.

The attacker then burst through a security checkpoint to stab a policeman in Old Palace Yard before sprinting about 30m towards an entrance of the House of Commons used by MPs.

Police draw their guns and fire at the man, killing him. Bystanders reported hearing at least three shots.

Police, paramedics and passers-by, including an MP, gave first aid to the police officer and the assailant before the attacker was taken by ambulance to hospital.

Parliament goes into lockdown, with armed police rushing to the scene. Prime Minister Theresa May who was leaving the House of Commons was whisked away in an armoured limousine by her security detail.

Proceedings in Parliament were suspended and MPs and peers asked to stay inside.

The attack occurred one year after 35 people including three perpetrators died in the Brussels bombings. The coordinated suicide bombings on March 22 2016 targeted Brussels Airport and a metro station in the centre of the city. Investigators found the assailants were part of a terrorist cell that had been involved in the November 2015 Paris attacks.