He said the man with a knife had been arrested, while police were examining the scene where the incident unfolded.
The witness said he had been working at the rear of a nearby property when the armed man sprinted into his view. He had been concerned for the welfare of the man on foot.
"A guy came running up the driveway and a white car followed him, with the police following up behind that. The guy had a small knife in hand, and he ran and jumped the fence. He looked terrified - pretty scared," he said.
"The guy in the white car chased him and went straight through one fence and then kind of got stuck, before he planted his boot and went through another fence and on to a third property."
The man said he heard one of the men shout out during the chase: "What the f*** are you doing?"
He said: "There was no one else in danger really, just the guy who was running, and he looked absolutely terrified."
Police refused to respond to questions put to them by the Wairarapa Times-Age about the incident, saying the investigation was ongoing.