The two teenagers, who dressed themselves in camouflage and attacked a mosque in San Diego, have been identified as Cain Clark and Caleb Vazquez.
Cain, 17, and Vazquez, 18, left home, armed with a 9mm handgun, a shotgun and a mini 14 - which had been stolen from Clark's mother's home - and descended onto the Islamic Center of San Diego at around 11.40am.
The horrific attack left three people dead outside of the place of worship, which also serves as a school, before the pair turned the guns on themselves.
Police described both teens as being dressed in camo fatigues and referred to the car they used as a 2018 BMW X1 SUV, on their radios shortly after the incident.
One of the victims was security guard Amin Abdullah, a father of eight children.
His friend Anees Faraj, a fellow security guard at the mosque who was not working, described the events as shocking and confirmed Amin as the guard who died.
San Diego Police Chief Scott Wahl said that Amin and his actions helped prevent an even deadlier attack and added: 'His actions were heroic and he undoubtedly saved lives today.'
TV footage from a helicopter showed armed response teams gathered outside a building, with one unidentified person lying in a pool of blood.
The place of worship, the largest in San Diego, is also home to the Al Rashid school, which educates children from kindergarten to the third grade. The imam of the mosque confirmed that no children were injured during the shooting.
Cain Clark, 17, was one of two teenagers who opened fire at a California mosque on Monday before taking his own life. Police named the other suspect as Caleb Vazquez, 18, who has not yet been pictured
Officers arrived on the scene in just four minutes, as they had already been searching for the teenagers after Clark's mother alerted cops to the threat
Images from the scene showed a red gasoline canister with a sticker resembling a Nazi SS logo, as a shotgun lay nearby
Who was Cain Clark?
Clark had been a San Diego School of Creative and Performing Arts student before he was enrolled in online learning in 2021, San Diego Unified School District spokesperson James Canning told CNN.
The teen continued to stay involved in his local high school's campus activities, including Madison High School's wrestling team who Clark competed with for two years in 2024 and 2025.
'They took all of their classes online. They talked with teachers online. That was the parent's choice to move them into that school,' Canning said.
This year, however, Clark did not participate in any events or activities, the outlet reported.
'It's important to point out that, this year, that student was not on campus at all,' Canning added.
The teenager had been on track to graduate and was said to have had no disciplinary record, aside from one report of punching someone in the leg in elementary school in 2015, Canning said.
A former teammate on the team said Clark had never expressed notions of Islamophobia, violence or racially charged viewpoints, and that the teenager had been finding community among the other wrestlers, according to the outlet.
'He seemed like he was a good kid,' the teammate, who has not been identified, told CNN.
The teen continued to stay involved in his local high school's campus activities, including Madison High School's wrestling team who Clark competed with for two years in 2024 and 2025
Panicked parents arrived at the scene to retrieve their children after the two teenage gunman opened fire
Two women were seen embracing as they left a reunification center following the shooting
'He didn't seem like he would do something like that. The kid was trying to fit in. He was always just trying his best - he was trying to fit in and find friends.'
However, a suicide note found on at Clark's home appeared to evidence anti-Islamic rhetoric and expressed notions of 'racial pride,' sources told the Los Angeles Times.
Hate speech was also found scrawled onto one of the guns.
The note, according to Wahl, 'began to trigger a larger threat assessment,' but he added that 'there was no specific threat, especially no specific threat to the Islamic Center.'
'It was just general hate kind of speech that I think covered a wide gamut,' he added.
Hours before the attack, Clark's mother had called law enforcement to report that her suicidal son and car were both missing as well as three weapons, and that he had left her home with another person, according to Wahl.
Clark's grandparents, David and Deborah Clark, told CNN that they were 'trying to process' the catastrophe and are 'very sorry for what happened.'
This is a developing story.