Four teenage girls have been taken to hospital following a single-vehicle crash in Bangor in the early hours of Sunday morning.
A 19-year-old, who police believe to be the driver, is in a critical condition.
The collision happened on the Ballycrochan Road and was reported to police at about 03:30 BST on Sunday.
Inspector Jonathan Francey said the car was a Fiat Grand Punto and is asking for anyone who may have captured dash-cam footage to contact them.
“We are appealing for witnesses or anyone who may have seen the vehicle travelling on the Ballycrochan between 3.15am and 3.30am this morning to please get in touch.”