Rhodes, 45, was found inside his pickup truck parked in a rural area of Brentwood at about 9:30 a.m., police reported.
"Our hearts and thoughts go out to the family in their time of need," the North County Fire Authority said in a prepared statement.
Rhodes had been reported missing after he apparently left for work at 4:45 a.m., but never arrived, Brentwood police reported.
The Contra Costa County coroner's office took custody of Rhodes' body.
