Dash cam footage has captured the moment a highway patrol police car was smashed by a 4WD while attempting to perform a U-turn on a NSW highway.

The crash took place on the Mitchell Highway near Orange in the final hours of the Easter weekend double demerits blitz on Monday afternoon, with vision of the grisly incident surfacing overnight.

The recording shows the officer slowing down as he drives towards the end of the merging lane.

Seconds after pulling in front of an oncoming Mitsubishi Triton being driven by a 46-year-old man, debris is sent flying across the road.

Three passengers were also in the Mitsubishi, including two children.

A 47-year-old female was taken to hospital with a fractured sternum, while the two children, aged eight and 12, were discharged without injuries.

The officer later said he detected a speeding driver heading in the opposite direction, so he turned to pursue them.

An investigation into the crash is now underway, with police questioning how the footage made its way onto social media.