More than 70 firefighters are tackling a blaze covering around 1,500 acres of Dartmoor.
Twelve fire crews are fighting the gorse blaze near Chat Tor and Lydford in the north west of the national park, which is being fanned by strong winds, Devon and Somerset Fire and Rescue said.
The firefighters have been drafted in from as far away as north Cornwall and are aided by local "commoners", who live and work on the moor, in attempting to control the fire, a spokesman said.
"The fire is currently being fanned by strong winds and the crews are at work using beaters," he said.
"Good progress is being made with firefighters using beaters along with the assistance of commoners also using beaters."