The alleged gunmen have been identified as Caleb Vasquez, 18, and Cain Clark, 17, the official told Reuters. They were found dead in their car after the shooting, apparently from self-inflicted gunshot wounds, police said on Monday.
Their names and the contents of the writings were previously reported by local media.
Police said on Monday that the attack was being investigated as a hate crime but declined to offer further details about a possible motive.
According to an FBI agent, the shooters appear to have been radicalized online.
The agent added that police have seized over 30 guns and a crossbow in searches of residences connected to the attack.
The guns used by the suspected shooters belonged to a parent of one of the individuals, reported the San Diego Police chief.
Clark’s mother is cooperating with authorities, the DOJ official added. Officers sprang into action on Monday after a call from one of the boy’s mothers, who described her son as suicidal and said he had run off with three of her guns and her vehicle, according to police.
Police initially raced to a local shopping mall and the boy’s school before calls came in about the shooting at the mosque.
The Islamic Center is the largest mosque in San Diego County and houses the Bright Horizon Academy. All students were safe and accounted for after Monday’s attack.
A fundraising effort organized by CAIR San Diego with the Islamic Center of San Diego has raised over $1.7 million for the family of slain security guard Amin Abdullah, who authorities have credited with preventing further bloodshed.
San Diego Mayor Todd Gloria told CNN on Tuesday that security would be beefed up across the city.
“There’s always a concern about other sick and twisted individuals who will take inspiration from this tragedy and try and replicate,” he said. “No expense will be spared in protecting the people of this city.”
