Inspector Ron Davis of Lake Illawarra Local Area Command said a 32-year-old man and two friends went to a home on the Princes Highway in Albion Park Rail, south of Wollongong, about 5.20pm on Wednesday.

A 41-year-old man inside the house allegedly armed himself with a knife and garden pitch fork, and stabbed the younger man in the neck and torso multiple times.

The fight is believed to have started inside the home but turned violent on an adjacent empty block of land about 30 metres away.

Inspector Davis said the two men knew each other but it was not clear what provoked the altercation.

"We are still making enquiries in that regard. The statements are only just being taken now."

There were several witnesses at the scene, one of whom contacted police, Inspector Davis said.

A woman had also been with the men inside the house before the fight.

The injured man was flown to St George Hospital with life-threatening injuries. He is in a critical condition.

The 41-year-old man was arrested at the scene and taken to hospital with a minor wound to his head. He remains under police guard.

Forensic specialists are currently at the scene.