The Robinson R-44 exploded about 11 p.m. Sunday at Corona Municipal Airport, 25 miles east of Anaheim. The pilot, who had not been identified, was the only person aboard, KTLA-TV, Los Angeles, reported Monday.
Federal Aviation Administration spokesman Ian Gregor said the blast occurred happened near the airport's fuel pumps, the TV station said.
Investigators said they believe the helicopter was in motion, though it was unclear if it was moving vertically or horizontally. The aircraft may have been taxiing when it clipped the canopy of the refueling area.
The pilot's body was severely burned. Authorities said dental records would be used to make an identification.