3 adults killed in shooting at Islamic Center of San Diego; both suspects dead: Police

The security guard appeared to play a "pivotal role" in keeping the shooting from "being much worse," police said at a news conference, noting that the victims were found out front of the center.

His actions were heroic," San Diego Police Chief Scott Wahl said of the security guard during a press briefing Monday. "Undoubtedly he saved lives today."

All children are safe, police said. Photos showed children being evacuated from the area.

One person suffered a "non-firearm-related injury while responding to the incident" and was taken to San Diego's Sharp Memorial Hospital, according to hospital officials.