A 65-year-old woman was treated for life threatening injuries and rushed to hospital with three others after a car crash on New Year's Day.
London Ambulance Service was called to a collision between two cars in Ducks Hill Road at the junction with Bury Street, Ruislip at around 2.45pm on January 1.
The woman, who suffered a head injury, was said to be in a serious condition. She was a passenger of a car driven by a man, aged 31, who was treated for potentially life changing injuries.
A 58-year-old woman, also a passenger in the car, was treated for non life threatening abdominal injuries. All three were taken by ambulance to St Mary's Hospital in Paddington.
The second driver, a 35-year-old man, was also taken to the hospital with a leg injury, shoulder and abdominal pain. Police later arrested him for drink driving and suspicion of causing serious injury by dangerous driving. He has been bailed to a date in mid February.
Four ambulance crews, a single responder and a hazardous area response team as well as London's Air Ambulance were sent to treat the four people involved in the smash.
As a result, Ducks Hill Road was closed in both directions by police for a number of hours yesterday. Heavy traffic built up in the area and the 331 bus route was diverted. The road opened up again at around 10pm.
Police enquiries are ongoing.