Police arrived to treat the incident as a barricade situation. Police waited for more than three hours before breaching the apartment.
A SWAT team on scene unsuccessfully attempted to contact the man inside. They stormed the apartment at about 4:25 p.m. and discovered the man's body, according to Irvine Police Lt. Henry Boggs.
Seven schools in the area were locked down between 1:30 p.m. and 2 p.m.