(dpa) - Nine firefighters were killed when a helicopter carrying them to help control a wildfire in northern California crashed and burned in a remote forest area, the Federal Aviation Authority said Wednesday.
Four other people on board the Sikorsky S-61 helicopter suffered severe burns.
The FAA said the helicopter crashed under "unknown circumstances" as it was being used to ferry firefighters to tackle the blaze in the Trinity-Shasta National Forest.
The Sikorsky S-61 helicopter is the only firefighting helicopter in the nation equipped to simultaneously carry both water and crew. It can carry up to 18 firefighters and drop up to 4,000 litres of water via a suspended bucket.