PORTLAND, Ore. -- Police said they were searching for some men who were reportedly armed after a fight on a bus Tuesday.

Police had eight to 10 blocks taped off in the area of North Fessenden Street and North Haven Avenue while they went door to door conducting the search.

For more than two hours, police armed with automatic rifles and utilizing K-9 teams searched the area and checked back yards.

The incident started around 1 p.m. when a report came in of a fight between three men on a TriMet bus, police said.

When officers responded, they found ammunition, which led them to believe that at least one of the men is armed with a handgun, police said.

That caused officers to step up the investigation and start a search for the three men, although they're not sure if a crime has been committed, police said.

Police Search For Man With Gun After Bus Fight