Trangmar managed to break free from the group after a struggle and then rode his quad bike into the front of the bar before fleeing.
No one was injured in the incident.
Bar co-owner Chris Dimond said his business partner, Ian "Curly" McErlich, who was behind the bar at the time, was "a bit freaked out".
There were about a dozen people in the bar and Mr Dimond said they suspected the offender, who had been banned from the bar following an earlier incident, was "very high on P".
"He pulled a gun on Curly and said give me your money and then shot the roof," he said.
"The locals worked out it was a single shot so they took him down."
Mr Dimond said the three men were local farmers in for "a quiet lemonade".
Following the incident they continued to have a few drinks and they seemed unruffled. They were joking about it, which was a way of dealing with the tension of the situation, he said.
Mr Dimond said the three took the risk of wrestling an armed man to protect Mr McErlich.
"They are all friends of his, and they just don't like scum.
"It was a pretty ballsy thing to do, probably a bit silly, but at the end of the day they made their call."
The weapon was a home made hand pistol "like a little pirate gun", and had been handed over to the police, he said.
So far they hadn't found the bullet in the wooden ceiling and it would stay there until the police wanted to find it.
The bar would open again today for business.
Meanwhile, armed police have set up a number of cordons and carried out searches of several properties around Otorohanga and Waitomo overnight looking for Trangmar.
Mr Van Kalken said last night's robbery was just one of number of incidents involving Trangmar over the weekend.
Police believed Trangmar threatened a neighbour at Honikiwi, 13km north west of Otorohanga, on Sunday night after being asked what he was doing with a motorcycle that was not his.
"A dispute broke out in which Trangmar punched the neighbour through the open window of his vehicle and then pointed a rifle at the man. The victim drove off and grabbed a firearm himself, discharging a warning shot."
Mr Van Kalken said Trangmar went home, grabbed a steel bar and returned to the neighbour's home to smash up several vehicles before police arrived.
Trangmar was not seen again until he allegedly stole a quad bike from an Otewa Rd property and rode it to an Island Rd house.
"Here we understand he pointed a firearm at a mother, demanding cash for a debt her partner allegedly owed before he fled and ended up at the Waitomo bar."
Police from across the Waikato and King Country have converged on Otorohanga and are assessing how to arrest Trangmar without anyone getting hurt. They are trying to contact him through his family.
Meanwhile anyone knowing where Trangmar was should ring 111 immediately, Mr Van Kalken said.
Police did not recommend people confront armed offenders, rather that they comply with any demands and contact police as soon as possible, he said.
- NZPA
