The staff member ran back into the club and locked the door.
The offender then approached a group of four backpackers, and again threatened them with a knife demanding they hand over property.
Another man was stabbed and the man left again empty-handed.
The two victims were taken through to Rotorua Hospital, with serious but not life-threatening injuries.
Inspector Steve Bullock credited praising the swift actions of officers in arrested the alleged offender.
"It was a fast moving situation with a number of scenes but officers reached the area within minutes and very quickly tracked down and arrested the alleged offender, preventing any risk to others," Mr Bullock said.
"These random acts of violence are rare, and the actions of staff tonight provide an assurance that police will act swiftly and decisively.
A 19-year-old local man is in custody having been arrested for assault.
Clare Ngatai, manager of the nearby Silver Fern Lodge, said one victim was an Australian tourist who was staying at the lodge. He was reportedly stabbed in the stomach.
The other man, stabbed in the chest, was visiting from out of town to look at properties for possible purchase, Ms Ngatai said.
The attacks came out of the blue as the offender was walking down the street with a woman, she said.
"Apparently it was random. There were two incidents, two different people, they weren't connected to each other."
Both men had been flown to Rotorua Hospital for treatment.
Ms Ngatai gave the men first aid but said neither seemed to be seriously injured.
"They seemed all right ... it looked like more muscle damage."