Two teenage attackers fatally shot three men at a mosque in San Diego, California, in a suspected hate crime, before taking their own lives, say police.
The shooting took place on Monday morning, two hours after the mother of one of the suspects called police to say her son had run away with a friend and was possibly suicidal.
Police were already on the hunt for the two when the attack at the Islamic Center of San Diego began, and they found three victims with gunshot wounds outside the front of the building.
Shortly afterwards, they received another call that shots had been fired nearby from a vehicle at a landscaper. Officers found the suspects – aged 17 and 18 – dead of self-inflicted wounds in a vehicle blocks away from the mosque.
Among the deceased victims was a security guard who worked at the centre and “played a pivotal role” in preventing the attack from being “much worse”, officials said.
“It’s fair to say his actions were heroic,” San Diego Police Chief Scott Wahl told a news conference. “Undoubtedly he saved lives today.”
Authorities have not yet identified the three victims by name. But the security guard was a father-of-eight, a person who knew him told the BBC’s US partner CBS.
Investigators said the motive for the attack was unknown, but it was presumed to be a hate crime because of the mosque, which is the largest in San Diego County, and because of writings attributed to one suspect.
Police were first called to the mosque at 11:43 local time (18:43 GMT) and “observed what appeared to be three deceased victims out front”, Wahl said.
“There were no officers involved in firing their weapons,” Wahl said, and there was no sign of any gunman.
About two hours before the attack, the mother of one of the suspects had called police to report that her son had left home with several of her guns and her car.
The woman said he had gone with a companion, and both were dressed in camouflage.
Wahl said police found the suspect’s behaviour to be “not consistent” with someone who is considered suicidal.
A note the youth left behind also included “generalised hate rhetoric and hate speech”, he said.
Wahl added that the note contained no specific threat to the mosque, or to any other location or individual.