Two female passengers were killed when the car they were travelling in plunged into undergrowth at the side of a road in Swindon, police said.
Another three male passengers are being treated in hospital with injuries, and two of them have been described as being "very poorly". All were aged 19 or 20 years.
Police received a report from another driver, who saw the car leave the road, at around 5am this morning. They found the grey Renault Clio some 20 metres from the A419.
Wiltshire Police are appealing for witnesses to call 101 and ask for PC Kevin Fry of the Serious Collision Investigation Team.