According to local reports from local media, one of the four is in a threatening condition.
A black Audi A3 crashed into a group of pedestrians crossing the road while turning into a side street in North End Road, behind Earl’s Court, officers say.
Witnesses described the scenes as a “battlefield” with “blood everywhere” after the collision.
A 19-year-old woman was arrested on suspicion of causing injury by dangerous driving – while a passenger in the Audi was treated for minor injuries.
A man in his 20s was thrown into the air after being hit head-on by the car and he remains in intensive care.
Three other casualties, a 56-year-old man and two men in their 20s, were given emergency treatment by paramedics before being transferred to hospital after the incident at 6.45pm yesterday.