UPDATED: Two people, believed to be cyclists, were taken to hospital with non-life threatening injuries after a car was driven into a group of riders outside the Palace of Westminster this morning. The Metropolitan Police have confirmed that they are treating the incident as a terrorist attack.
The incident happened at 0737 according to Scotland Yard, who cordoned off a large area of Westminster.
The driver of the vehicle, who has been arrested on suspicion of having committed terror offences, ploughed through a group of around 10 cyclists on the south-east corner of Parliament Square before hitting a crash barrier outside the Palace of Westminster.
Three cyclists were injured. Two, a man and a woman, were treated at hospital for their injuries but have since been released, while a third was treated at the scene.
Another cyclist was shown on video chasing after the car on foot just before it hit the barrier outside Parliament.
Armed police officers were on the scene immediately and took the driver away in handcuffs.
Cycle Superhighway 3, the most popular cycle route in London, runs through Parliament Square though the cyclists who were hit were not on that route but on the other side of the square..
Eyewitnesses told BBC News that they believed the motorist drove into the cyclists on purpose.
Barry Williams, who works for the BBC at its Millbank location, said: "I heard lots of screams and turned round.
"The car went onto the wrong side of the road to where cyclists were waiting at lights and ploughed into them.
"Then it swerved back across the road and accelerated as fast as possible and hit the barrier at full pelt.
"It was a small silver car and he hit it at such speed the car actually lifted off the ground and bounced.
"Then the police just jumped. Two officers managed to leap over the security barriers and then the armed police vehicles all sped towards the scene."
BBC reporter Callum May, speaking from Westminster, said: "Parliament Square is now ringed by blue police tape. There is a large group of armed officers in the square.
"Paramedics are treating a small group of people sitting on the ground outside the Palace of Westminster.
"They are wrapped in silver blankets. One eyewitness, who declined to give his name, said he saw a small hatchback drive into a group of cyclists and then into the barrier outside the Palace of Westminster.
“The man said that the driver's action appeared deliberate."
Scotland Yard confirmed that a man was arrested and is being held at a police station in south London.
Mayor of London Sadiq Khan has
Born in Scotland, Simon moved to London aged seven and now lives in the Oxfordshire Cotswolds with his miniature schnauzer, Elodie. He fell in love with cycling one Saturday morning in 1994 while living in Italy when Milan-San Remo went past his front door. A daily cycle commuter in London back before riding to work started to boom, he's been news editor at road.cc since 2009. Handily for work, he speaks French and Italian. He doesn't get to ride his Colnago as often as he'd like, and freely admits he's much more adept at cooking than fettling with bikes.