An 'altercation' near Quirindi is alleged to have broken out between the two men, who police believe were known to each other.

One 28-year-old man suffered serious head injuries, and was airlifted from Quirindi hospital after being placed on life support.

Another 28-year-old man was later arrested at a property in Willow Tree and taken into police custody, where he remains.

At about 12.15am, officers from the Oxley Police District were notified of a man presenting to the hospital with serious head injuries.

Following their inquiries into the incident, police officers attended a home in Willow Tree to make the arrest.

The man was taken back to Tamworth Police Station where he was charged over the incident.

He was charged with assault occasioning grievous bodily harm and refused bail, and is set to appear before Tamworth Local Court on Monday.

The other man remains at John Hunter Hospital in a serious condition.

Just after 1:30am, the Westpac Rescue Helicopter was sent out to Quirindi by Ambulance New South Wales to attend to him and his serious injuries.

He was stabilised by local Ambulance Paramedics before the chopper and the Critical Care Medical Team landed to continue treatment.

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He was placed on life support before being flown directly to John Hunter Hospital in a critical condition.

His was described as being in a serious condition by a police spokesperson on Sunday evening.

Anyone with any information in relation to this incident is urged to contact Crime Stoppers on 1800 333 000 or at nsw.crimestoppers.com.au.