Four people were trapped, and two are in a serious condition after a car rolled off a rural North Canterbury road early this morning.

Emergency services were called to the single-vehicle crash on State Highway 7, between McRaes Rd and Mt Alexander Rd, near Waikari, about 6.40am.

Fire and Emergency New Zealand said four people were trapped in the vehicle following the crash.

Hato Hone St John said three ambulances, a helicopter, rapid response unit, and two operations managers attended.

Three patients were transported to Christchurch Hospital, two in serious condition and one in moderate condition.

One of the serious condition patients was taken to hospital by helicopter, with the others by road ambulance.

Crews from four stations responded and have since extricated all occupants.

Several crews remain at the scene and the road is closed.