PORTLAND, Ore. -- A man was being assaulted when he stabbed another man in self-defense on a TriMet MAX train Tuesday afternoon in Portland, according to police.

The man who was stabbed initially confronted the other man and a woman, accused them of talking about him and demanded they tell him what they were saying, Portland police said.

That man then began punching the other man, who responded by wielding a knife and stabbing his attacker, police said.

The train then arrived at the Northwest 1st Avenue and Davis Street stop, where officers detained both men.

The man who was stabbed was provided medical aid and taken to a hospital with non-life-threatening injuries.

The man who was punched was interviewed by detectives, who determined he acted in self-defense.

No one has been charged with a crime at this time. An investigation is ongoing. The case will be forwarded to the Multnomah County District Attorney's Office.

Anyone with information about the confrontation is asked to contact Detective Chris Traynor at 503-823-0889.