Police put diversions in place shortly after 4pm. The highway remained closed for most of the night as investigators undertook the task of determining how the two vehicles collided on a sweeping bend not far from Jacob and Joseph Creek.

Emergency services including highway patrol and general duties police, paramedics, Volunteer Rescue Association personnel and the Rural Fire Service were called to the highway at Gaspard Road, about 9km north of Wallabadah, after a triple-0 call.

Police had released few details last night, but confirmed one female had died.

A man, believed to be in his 40s, was rushed to Tamworth hospital with serious head and chest injuries. The Westpac Rescue Helicopter Service was on standby last night to transfer the patient to the region’s specialist trauma centre, John Hunter Hospital at Newcastle.

His condition was not known at the time of going to press.

The woman was believed to have been the driver of the other vehicle. Police said she died at the scene.

The vehicles involved in the crash were not identified, but one is believed to have been a four-wheel-drive.

Police were unable to estimate how long the highway was likely to be blocked for. It was expected to reopen early this morning.

Northbound traffic was diverted along the Kamilaroi Highway at Willow Tree through Quirindi and Werris Creek Road to Tamworth.

Motorists travelling south were diverted just outside Tamworth along Burgmanns Lane and Werris Creek Road to Quirindi.

Local traffic wanting to access Kingswood Estate, Whitehouse Lane and other local roads off the highway were allowed to pass.

Crash investigators attached to the Oxley Local Area Command were sent to examine the scene.

Police said last night the highway would not be reopened until they had completed their investigations and all crash debris had been removed from the scene.