SAN FRANCISCO (AP) — Fire raging through rugged, dense terrain complicated efforts Thursday to recover victims and evidence from a remote forested area in northern California where a firefighting helicopter crashed. Nine people were presumed dead, but four others were rescued.

The aircraft was carrying 11 firefighters and two pilots when it went down and was destroyed by fire Tuesday night in the Shasta-Trinity National Forest, according to the Federal Aviation Administration and National Transportation Safety Board. The crash occurred just after the helicopter had picked up firefighters and lifted off from a small clearing to take them back to camp, officials said.

Four injured people — three firefighters and a pilot — were flown to hospitals. They were rescued from the burning wreckage by firefighters on the ground who had been waiting for another helicopter to pick them up, said Jennifer Rabuck, spokeswoman for the U.S. Forest Service.