HAYWARD -- A stabbing victim arrived at Eden Medical Center early Monday morning and said he'd been attacked along Mission Boulevard, a police spokesman said.

The man, whose identity was not immediately known, walked into the Castro Valley hospital at 3:56 a.m. with a friend, said Sgt. Mark Ormsby. The man told hospital workers he'd been stabbed by an unknown suspect while walking on Mission Boulevard, but his friend told employees that he'd been stabbed in Oakland.

Oakland police arrived but when they attempted to interview the man's friend, they could not find him.

The victim underwent emergency surgery on Monday morning and was expected to survive. Police did not say where on his body or how many times he was stabbed. Investigators were waiting to interview him further, Ormsby said.

Anyone with information about the stabbing is asked to call police at 510-293-7000 or the anonymous tip line: 510-293-7197.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.