The helicopter was among those fighting a fire in the Fishlake National Forest. The crash ignited a new fire that spread to connect with the existing blaze, which has now scorched nearly 174 square miles (nearly 451quare kilometres).

Officials did not identify the pilots but said they were employed by Helicopter Transport Services, which was contracted by the US Forest Service.

Initially officials said they were unable to reach the crash site because of the fire. Then, crews were able to enter the area and confirmed the deaths.