Chula Vista firefighters found a body inside a burning trailer on Sunday.
Fire Battalion Chief David Albright said the body was found in a trailer behind a pull business on Mason Street near the corner of Britton Street.
Albright said it appears the victim lived in that trailer.
Firefighters received an emergency call in the afternoon and moments after showing up were able to enter the trailer.
Both arson investigators and Chula Vista police are finding out how the fire started and if the person died at the scene.
Authorities did not release details of the victim's identity.