Two people have died, and four others have been taken to hospital following a multivehicle crash on the NSW mid-north coast on Monday.

Emergency services were called to the northbound lane of the M1 Motorway near Nabiac, about 30 kilometres south of Taree, following reports of a crash about 9.30am.

Officers found a Nissan SUV and a Toyota LandCruiser, which was pulling a caravan, had crashed before the SUV hit a prime mover.

Two people from the Nissan SUV died at the scene and are yet to be formally identified. A black chihuahua that was travelling in the car was uninjured and is believed to still be in the area.

The driver and three passengers from the Toyota LandCruiser – a man aged 42, a woman aged 43 and two children aged eight and nine – were treated by NSW Ambulance paramedics before being taken to John Hunter Hospital for further treatment.

The driver of the prime mover was uninjured and was taken to Manning Base Hospital for mandatory testing.

Police have launched an investigation into the cause of the incident and urge anyone with dashcam vision or information to contact Manning-Great Lakes Police or Crime Stoppers on 1800 333 000.

Police are also asking for assistance to locate the chihuahua, which answers to the name Armani. It fled the scene following the crash.