'Scarily calm' man in Newcastle stand-off

A man wanted over a triple stabbing is refusing to budge from a residential rooftop in Newcastle after spending more than nine hours in a stand-off with police.

In a surprise twist, it's been revealed the man also allegedly stole a car owned by Australian Rugby Union chief executive Bill Pulver before climbing on to the roof of the townhouse in Tighes Hill around midday Tuesday.

The man is wanted over Monday night's triple stabbing at a Sydney gym and two subsequent armed robberies at service stations.

Three men are in hospital after they were stabbed at the fitness centre in Sydney's Brookvale about 8pm on Monday, with the attacker then driving away in the stolen vehicle before allegedly robbing two service stations in Newcastle.

Mr Pulver's car was stolen at a car wash.

Some residents of the street weren't being allowed inside their homes on Tuesday night with several roads blocked off for the police operation as the man refused to come down from the roof.

With the sun setting, police were using large spotlights on the man as he wandered on the roof in just a pair of shorts.

Sam Phillip Harrison, a resident in Mayfield, had finished work to find the scene with several ambulances, police cars and the operation in full swing.

He said the man didn't appear angry and wasn't responding to police.

"He doesn't look aggravated," Mr Harrison told AAP.

"He looks scarily calm about the whole thing."

Police said they would wait all night.

"We'll negotiate with him as long as it takes," Newcastle police crime manager Detective Inspector Peter Mahon told Fairfax Media.