A helicopter crashed in the Shasta-Trinity National Forest on Tuesday. The helicopter was carrying firefighters back to base  and nine of the them are missing and believed to be dead. Four others who were on board of the chopper were critically burned.

Officials couldn’t identify all the passengeres until now. The Sikorksy S-61 helicopter crashed at 7:45 p.m. while it was taking off from a remote site 35 miles northwest of Redding, in Northern California. The helicopter was carrying the firefighters back to its base in Junction City.

Helispot 44, the place where it crashed was on a steep rugged terrain with underbrush, as officials announced. Ten of the firefighters involved in the accident work for Merlin, Ore.-based Grayback Forestry, a long-established private firefighter’s contractor.

Investigators are still trying to find out why did the Sikorsky S-61 crash. Three of the survivors were identified as Michael Brown, 20, Jonathan Frohreich, 18 and Rick Schroder, 42.

All of the firefighters were part of the team of 1,200 firefighters who were fighting the fires in Iron and Alps, which burned 86,000 acres. The fire started on June 21 because of lighting and it was 86% contained.

Two of the injured firefighters on the helicopter and the pilot were taken to UC Davis Regional Burn Center in Sacramento. Two of them were in critical condition and the third was in the Intensive Care Unit. A fourth injured person was taken to Mercy Medical Center in Redding as his condition is serious.