NSW Ambulance said the 41-year-old suffered serious head injuries in the crash, 10km north of Armidale.

The spokesperson said the region’s rescue helicopter was requested and paramedics rushed the patient to Armidale hospital in a critical condition.

​The Westpac Rescue Helicopter was tasked from Tamworth and then airlifted the woman on Wednesday night to John Hunter Hospital in Newcastle.

Four vehicles were involved in the crash and police took three other drivers to hospital for mandatory testing. 

Investigators remain at the crash scene on Wednesday night, near Puddledock Road.

Live Traffic NSW said motorists who need to travel between Armidale and Guyra can use Guyra Road and Waterfall Way as an alternative route.

This diversion is suitable for all types of vehicles, but adds about one hour to the journey.

Motorists should allow plenty of extra travel time, the spokesperson said.

EMERGENCY services are at the scene of a serious head-on crash on the New England Highway between Armidale and Guyra.

The crash, which saw one vehicle flip onto its roof following the impact, occurred shortly before 3pm, about 10km north of Armidale, near Macanna Road.

Police, paramedics and SES crews are at the scene, which has closed both lanes of the highway.

Paramedics are assessing two patients at the scene with one woman reported to be in a critical condition.

The 41-year-old woman suffered a serious head injury.

The Westpac Rescue Helicopter has been alerted, but the woman is being rushed to a nearby hospital via ambulance, a spokesperson for NSW Ambulance said. Five ambulance units are at the scene.

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Another driver is being assessed at the scene by paramedics.

The road is blocked in both directions and is expected to remain closed for sometime with reports of debris from the wreckages strewn across the road.

Live Traffic NSW said motorists should avoid the area with traffic being diverted via Guyra Road and Waterfall Way. Drivers are asked to allow extra time.

More to come.