Police are looking for a man who they believe is responsible for stabbing another patron inside the State Theatre in Portland following a dispute during a concert Sunday night.

The 29-year-old Norway man who was injured is expected to survive, police said. He has not been identified.

Police responded to the concert venue about 11:11 p.m. after staff discovered someone in the crowd was injured.

Officers met with the victim in the Congress Street venue’s lobby, where they saw he was suffering from at least one puncture wound.

Portland Police Commander James Sweatt said theater staff made the decision to end the show early, prompting the evacuation of about 1,800 people. Police interviewed the patrons who matched the suspect description as they left the venue.

Sweatt said everyone was cooperative, and that detectives have already previewed security footage from cameras inside.

The suspect is described as a white male between 28 and 33 years old. He is 5 feet, 8 inches to 5 feet, 11 inches tall with an average build and short black hair. He was clean shaven and wearing a collared jacket, police said.

The all-ages show featuring Dirty Heads with Jukebox the Ghost and Just Loud was nearly sold out, the State Theatre said in a Facebook post.

Lauren Wayne, general manager at the State Theatre, said it is still not clear what type of weapon was used in the attack, and said like at all events at the venue, everyone permitted inside was subject to a bag search and metal detector wands by security staff.

“Again, the police are handling this,” Wayne said. “I can’t comment what the weapon was, if there was a weapon.”

She said the State Theatre has not had any incidents involving a weapon in the eight years that the venue has been open.

Wayne said closed-circuit security camera coverage in the venue is extensive, and that all footage would be turned over to the police.

“It was an unfortunate situation, but we’re thankful the (crowd) exit was smooth and as safe as possible,” she said.

Dirty Heads is a quintet with heavy hip-hop, reggae and alternative rock influences. The band hails from Orange County, California.

Anyone with information about what happened should contact police at 874-8575.