Two Australian firefighters have spent hours hiding in a US forest as two shooters opened fire on them, according to details released in the official review of the incident.

The Australians were part of a group surveying White Pass in Washington state, which has been damaged by fire.

Despite the men wearing bright yellow shirts and hard hats and waving at the shooters, they opened fire several times using rifles fitted with telescopic lenses. 

The men were later evacuated by helicopter three hours after the incident began and the shooters have been issued with violation notices by the USDA Forest Service.