Three people have been killed in a shooting at a mosque in San Diego, California, which officials believe was perpetrated by two teenage attackers.
The shooting took place on Monday morning as officers were investigating a call about a possibly suicidal teen who had run away from home.
At 11:43 local time (19:43 BST), police were called to a shooting at the Islamic Center of San Diego, and found three victims who had been shot in the front of the building.
Shortly after, they received another call that shots had been fired nearby at a landscaper from a vehicle. When officers arrived at the second scene, they found the suspects - ages 17 and 18 - dead of self-inflicted wounds.
Among the deceased victims was a security guard who worked at the centre and heroically prevented more people from dying, officials said without providing further details.
The incident is being investigated as a hate crime, according to the FBI, due to writings found by one of the suspect's mother.
Police were first called to the centre at 11:43 local time (19:43 BST) and "observed what appeared to be three deceased victims out front", San Diego Police Chief Scott Wahl said during a news conference on Monday.
"There were no officers involved in firing their weapons," Wahl said, and there was no sign of any gunman.
Before the attack, the mother of one of the suspects had called officers at 9:42 local time, and reported that when her son left, he took several of her guns and her car.
The woman said he had gone with a companion, and both were dressed in camouflage. A note the youth left behind included "generalised hate rhetoric and hate speech".
Wahl said police found the suspect's behaviour to be "not consistent" with someone who is considered suicidal. Investigators then went to a local high school, where one of the teens studied, as well as a shopping mall where the car had been reported seen.
Wahl added that the motive for the attack is currently not known, but presumed to be a hate crime due to the location and the prominence of the mosque. He added that the note contained no specific threat to the mosque, or to any other location or individual.
When the shooting took place, officers were still speaking to the mother and were only a few blocks away from the mosque.
Those officers, upon finding the three victims outside the building, rushed inside and began following active shooter protocols.
While they were clearing rooms, more reports came in of another shooting nearby.
The suspects had allegedly opened fire from their car at the landscaper, who was uninjured. Wahl said he may have been shot in the head, with the bullet deflected by his hard hat, although this has yet to be confirmed.
When police arrived at the second scene, they discovered the dead bodies of both suspects.
Children were present when the incident unfolded on Monday. The Islamic Center campus houses the Al Rashid School, which offers religion and language courses.
Aerial video from the scene on Monday showed children holding hands and being escorted through a parking lot of the centre as police responded.
Nearby schools were placed on lockdown as police responded to the area.
The FBI asked for the public to supply any information that may be able to assist with the investigation.
A witness speaking to CBS News, the BBC's US partner, said he heard up to 30 gunshots from what sounded like "a semi-automatic weapon".
He said he first heard about a dozen shots, then a pause, then another possibly dozen shots.
The man, who is retired and was eating lunch at home, said he called 911 and that police arrived within "five to 10 minutes".
The mosque gets very busy during holidays, he said.
"It's a good thing it didn't happen on a Friday, because the streets would be full of people," he added.
Imam Taha Hassane, the director of the Islamic Center of San Diego said at a news conference: "It is extremely outrageous to target a place of worship."
The facility, "is a house of worship, not a battlefield".
The Muslim community is currently preparing for one of its holiest seasons and its biggest feasts.
It's days before Eid al-Adha or the "Festival of Sacrifice," one of the two major Muslim holidays, where families celebrate and commemorate the obedience of Prophet Ibrahim.
California Governor Gavin Newsom released a statement saying that he is "horrified by today's violent attack" at the centre, "where families and children gather, and neighbors worship in peace and fellowship."
The state "will not tolerate acts of terror or intimidation against communities of faith," Newsom added.
Asked about the shooting on Monday, US President Donald Trump called it a "terrible situation".
"I've been given some early updates but we're going to be going back and looking at it very strongly," he said during an unrelated White House event.
