Swimmer at San Quentin Beach attacked with baseball bat

At approximately 7PM on July 16, a man who had been swimming was hit in the back of the head with a baseball bat as he was coming out of the water. The attacker was wearing all black with a hood and a face mask. He was carrying a black baseball bat and had a pitbull with him. The man escaped. If anyone has any more information, please contact the Marin County Sheriff.