Investigators have discovered what officials described as “anti-Islamic writings” inside a vehicle connected to the two teenagers accused of carrying out the deadly shooting at a mosque in San Diego, according to a U.S. Department of Justice official familiar with the case.

The attack took place on Monday (18 May) at the Islamic Centre of San Diego and left three people dead. Authorities later found the two suspects dead inside a car from what police believe were self-inflicted gunshot wounds.

The suspects have been identified as 18-year-old Caleb Vasquez and 17-year-old Cain Clark.

Police are treating the incident as a hate crime, although they have not yet released full details about a possible motive.

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Police response began with mother’s emergency call

The investigation revealed that officers were first alerted after one of the boys’ mothers contacted police. She reportedly told authorities that her son was suicidal and had fled in her vehicle carrying three firearms.

Police initially rushed to a nearby shopping centre and the teenager’s school while trying to track him down. Shortly afterwards, emergency calls began coming in from the mosque.

A Department of Justice official said Clark’s mother has been cooperating fully with investigators.

Mosque community left reeling

The Islamic Centre of San Diego is the largest mosque in San Diego County and is also home to the Bright Horizon Academy. Officials confirmed that all pupils at the school were safely accounted for following the attack.

Residents living near the mosque described scenes of shock and confusion as helicopters circled overhead and emergency vehicles flooded the area.

Rick Rodriguez, who lives nearby, said the tragedy would leave a lasting mark on the community.

“I feel for all the people and kids,” he said. “Now they have to think about this for the rest of their lives.”

Security guard praised as a hero

Much of the community’s grief has centred on Amin Abdullah, a security guard killed during the shooting. Authorities believe his actions helped prevent even greater loss of life.

A fundraising campaign organised by CAIR San Diego alongside the Islamic Centre has already raised more than $1.7 million for Abdullah’s family.

Ahmet Kuru, a political science professor at San Diego State University who attended the mosque with Abdullah, described him as a deeply respected figure.

“Amin was always there greeting people,” Kuru said. “He was a hero and someone the community loved.”

Neighbours stunned by developments

On Monday evening, police sealed off a residential property believed to be linked to one of the suspects. By the next morning, the police tape had been removed and neighbours gathered outside trying to make sense of events.

Residents said the family kept largely to themselves, though the house was known locally for elaborate Halloween decorations. A monster truck remained parked in the driveway as investigators continued their work.

Jessica Delapena, who walks past the house daily, said the revelations were difficult to process.

“We walk past this house every morning,” she said. “It’s shocking.”

Security increased across San Diego

San Diego Mayor Todd Gloria said security would be strengthened across the city in response to the attack.

Speaking to CNN, Gloria warned of concerns that others could attempt to imitate the violence.

“There’s always a concern about other sick and twisted individuals who may take inspiration from this tragedy,” he said. “No expense will be spared in protecting the people of this city.”

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Rising concerns over Islamophobia

The shooting comes amid growing concern about anti-Muslim hostility in the United States.

The Council on American-Islamic Relations said it received a record 8,683 complaints involving anti-Muslim and anti-Arab incidents in 2025. The cases included allegations of workplace discrimination, immigration-related abuse and hate incidents.

Following the attack, far-right activist Laura Loomer posted claims on social media suggesting, without evidence, that Muslims may have staged the attack to encourage tougher Islamophobia laws.

Kuru dismissed such comments as inflammatory attempts to gain attention.

“Some people say crazy things to get public attention,” he said.

U.S. President Donald Trump later described the shooting as a “terrible situation” and said his administration would examine the case closely.

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News San Diego Islamic centre Mass shooting California Islamophobia Hate Crime