SAN LEANDRO -- Police are hunting for an attacker who they say brutally beat a Safeway manager inside the store just south of Victoria Park on Monday morning.

A motive for the attack, witnessed by customers, was not immediately known, police said.

Officers were called at 10:55 a.m. to the grocery store at 555 Bancroft Ave. for a report of a battery involving seriously bodily injury, said Lt. Randy Brandt.

Brandt said the man walked up to the manager inside the store, had a brief conversation with him and, for unknown reasons, punched the manager in the head, knocking him to the ground.

The manager fell and suffered serious injuries, Brandt said.

The suspect ran out the front door toward Bancroft Avenue and then in an unknown direction.

The manager was taken to a hospital for treatment and remained hospitalized on Tuesday.

Police described the suspect as a black man, age 20, 5 feet 10 inches tall, with an athletic build. He wore a hat, gray shirt and bluejeans.

Anyone with information about the suspect or this case is asked to call police at 510-577-3230 or contact the Anonymous Tip Line at 510-577-3278.

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