Authorities say 17-year-old Cain Clark was one of two teens who opened fire at a San Diego mosque before taking their own lives; his mother had warned he was suicidal and armed, while racist messages, a suicide note and a Nazi symbol were later found

The complex is home to the Al Rashid school where crowds of young students were seen being evacuated on Monday following reports of the shooting.

Both teenagers are believed to have died from self-inflicted gunshot wounds.