Authorities say Nicholas Lovato of Menifee and four other people had hiked into the Santa Margarita Ecological Reserve, which is off limits to the public, on Monday. He was sitting on a rock outcropping when it suddenly gave way.
Lovato fell about 30 feet into a canyon and was struck by a falling boulder. Officials say he died instantly.
His body was recovered by helicopter Tuesday morning.
The Associated Press contributed to this report.