SAN DIEGO -- A Marine was stabbed early Saturday outside a Pacific Beach bar by a civilian who thought he was breaking up a fight, San Diego police said.

The two Marines had been drinking and started play fighting about whether they were too drunk to drive at 2 a.m. in the 4400 block of Cass Street, said San Diego police Officer Brad Ruff.

A third man interceded and stabbed one of the Marines, before another Marine stepped in to put a stop to the incident, Ruff said.

The three left in a cab. The victim didn't realize he had been stabbed until they arrived at the gate of the Marine Corps Air Station at Miramar. Paramedics were called and the man was taken to a hospital with stab wounds to his chest and one of his arms.

San Diego police are seeking the knife-wielding suspect, described as a white man, about 5 feet 8-9 inches tall, with dirty blond hair. He was wearing a black shirt and blue jeans.