An unprovoked attack early Friday in Portland's Old Town Chinatown neighborhood left a man wounded, police say.

The stabbing victim and a friend were walking on Northwest First Avenue near Couch Street when an "unknown" man who was "acting psychotic" approached him and stabbed him in the arm without provocation, police said. The victim and his friend yelled at the assailant, who ran away and wasn't found, according to police.

The assailant was described as a bald man in his mid-20s, about 6 feet tall and wearing dark clothes, according to police.

Officers initially responded about 3:25 a.m. The stabbing victim was rushed to a hospital and was treated and released.

— Jim Ryan