An apartment complex resident who witnessed part of the incident told television station KFMB-TV, the CBS affiliate in San Diego, that five to seven victims were shot, before the gunman was slain on the scene by police. The condition of the wounded was unknown.
San Diego police were not immediately available to confirm details of the shooting, which was reported to have begun shortly after 6 p.m. local time at the Ja Jolla Crossroads Apartments in the University City section of San Diego.
A Fox News affiliate station reported multiple victims were shot before the gunman was himself shot.
The KFMB eyewitness, who identified himself only as a Crossroads resident named John, said he saw the suspect "sitting, drinking a beer in one hand with a gun out in the other" in the pool area of the apartment complex.
He said he and his wife, a nurse, saw "three people laying on the ground shot" and that he also saw one wounded victim trying to crawl to another to give assistance.
He said two police officers who arrived on the scene confronted the gunman, who exchanged gunfire with police before he was shot. The eyewitness also said some of the victims were taken away in cars to the hospital before fire department personnel or paramedics made it to the scene.