Forest fires have broken out in parts of south Donegal, but have so far been contained.
The blaze at Glengesh was spreading so fast that fire fighters had to call the Defence Forces for assistance.
So far, an Air Corps AW 139 helicopter fitted with a specialist under slung Bambi Bucket has dropped more than 21,000 litres of water on the flames.
"Operations have so far been successful in containing the spread of the fire," said a Defence Forces statement.
The helicopter also brought a fire safety qualified army engineer to the scene early today to assess the situation from the air and advise on the use of military assets.