Orange County Fire Authority Capt. Tony Bomarito said fire crews and Tustin police were called at about 1:45 p.m. to the 13800 block of Redhill Avenue about a man trapped inside the vacant car wash building.
When fire crews arrived, they found the unidentified victim dead.
Investigators with Tustin police are trying to find out how the man died and are working on trying to find any witnesses to what happened, fire officials said.