Several people were injured as a double-decker bus crashed into several cars on a busy street in the West End.
Paramedics were scrambled to Haymarket near Piccadilly Circus station shortly after midday on Wednesday.
Dramatic pictures from the scene show a Number 3 bus, which was heading towards Crystal Palace, with its windscreen completely shattered.
Others show a taxi that appeared to be involved in the pile-up on the pavement with its front bumper hanging off.
A London Ambulance Service (LAS) spokesman said seven patients were treated at the scene.
He added that three of them - two women and one man - were taken to hospital after suffering minor injuries.
On its response units’ Twitter page, LAS staff thanked baristas from the nearby Caffe Concerto who handed out hot drinks following the incident.
No one from the café was available for comment.
In statement, LAS said: “We were called at 12.10pm to Haymarket, Westminster to reports of a road traffic collision.
“We sent two ambulance crews, a cycle responder, two single responders in cars and an incident response officer to the scene.
“We assessed seven patients at the scene and took three of them to hospital with minor injuries - two women and one man.”
Scotland Yard said a number of vehicles were involved in the crash.
Roads were closed off while officers and paramedics dealt with the incident.
