A truck driver has been killed in a horror crash on the New South Wales Mid North Coast overnight.

The two B-double trucks were travelling north on the Pacific Highway, near Nabiac, when they collided at about midnight.

Footage of the wreckage shows the complete and utter carnage that took place.

One of the drivers died at the scene and is yet to be formally identified.

The second driver has been taken to John Hunter Hospital in Newcastle in a stable condition.

The Crash Investigation Unit are investigating the circumstances surrounding the crash and will prepare a report for the Coroner.

All northbound lanes remain closed and a contra-flow is in place, with heavy traffic in both directions.