Firefighter Nick Barrios was walking a woman to her car when they were confronted by a man on the street.
Trejo fired several rounds, shooting the firefighter in the street. The woman was not injured.
The woman was involved in a relationship with Trejo several months earlier that had ended, Blevins said. Police did not know what relationship the woman had with Barrios.
After Barrios was shot, police believe the man followed the woman into the house where he shot and killed himself in front of her.
Riverside police and firefighter-paramedics arrived to find Barrios and took him to a local hospital, where he died from his injuries.
Barrios was a 12-year veteran with department, joining the city in 1998. Riverside firefighters deferred any comment Sunday night to Riverside police.
Sources: PE.com - Link, KTLA Link