Two firefighters have been shot dead with a high-powered rifle after responding to a brush fire in Idaho, say US officials At least one active shooter is hiding on a mountain where the killings took place, a law enforcement source has told CBS, the BBC's US partner Earlier, a local sheriff said: "We don't know how many suspects are up there, and we don't know how many casualties there are" Authorities have deployed helicopters with heat-seeking technology as the manhunt continues, but they are experiencing difficulty due to smoke from the ongoing wildfire The FBI says it remains "an active and very dangerous scene" Two firefighters shot dead in Idaho as police warn of 'sniper fire' on mountain
