Firefighters were tonight tackling a major mountain blaze in Co Armagh.
Up to 100 crew members were on Slieve Gullion near Meigh where a tree plantation was burning.
A total of 17 appliances were brought in to gain control of the flames as they spread across an area of 200,000 sq metres.
A police helicopter has also been used to identify where the fire is raging at its most fierce. Group commander Aidan Magennis said efforts to extinguish the blaze were being hampered by its location and the continuing heatwave.
"There were two fire fronts which we have now reduced down to one," he said. "Slieve Gullion is a beautiful part of the country but it's quite hilly. Because of the rough terrain it's difficult trying to access the fire.
"Temperatures are also in excess of 26 degrees which is quite tough on the fire fighters. We have had to dispatch additional water supplies for our guys."
Although it was too early to say how the blaze started, Mr Magennis suggested even a glass bottle discarded by picnickers could have ignited it in the current hot weather.
The Northern Ireland Fire and Rescue Service also revealed it has received more than 450 calls in the past 24 hours.