Three California Department of Fish and Game biologists were killed Tuesday in a helicopter crash in Sierra National Forest, and officials fear the pilot has died as well.
The crash occurred south of Redinger Lake after the Bell 206 helicopter struck a power line, Southern California Edison said.
The biologists were conducting routine deer surveys in a remote, wooded area near the border of Fresno and Madera counties.
"This is just such a tragedy," said John Baker, the agency's Central District assistant chief. "I've just started sending out my officers to the residences to make the notifications."
The crash has sparked a fire that has made the site inaccessible, but light winds and moisture slowed the fire's movement, Madera County sheriff's spokeswoman Erica Stuart said.
Harry Morse, a Fish and Game spokesman, said the helicopter belonged to Landells Aviation of Desert Hot Springs.
A woman who answered the phone at Landells confirmed one of its helicopters was involved in the crash but could not provide other details and would not give her name.