The Northern Ireland Fire Service are attending a 2.5 mile long gorse fire in County Tyrone.
Seven fire engines and 56 firefighters are at the scene of the fire at Barony Road, Mountfield, Omagh.
It's the second gorse fire reported in County Tyrone within the last 24 hours.
On Wednesday a "dramatic" wildfire came within metres of mountainside homes at Loughmacrory and local people used shovels and water carriers to prevent the homes from catching fire.
Commenting on the latest fire at Mountfield, a spokesperson for the Northern Ireland Fire Service said: "Dealing with fires such as this one, which at this stage appears to have been started deliberately, unnecessarily draws precious resources away from where they are needed most, which is protecting our community.
"NIFRS would appeal to anyone involved in starting fires such as this to please stop and think about the impact of their actions and to cease this activity immediately."
The spokesperson added: "It is most important that we all play our part in protecting our communities during this national emergency, and to ensure that we do not expose firefighters to additional risks from Covid-19 and to add unnecessary pressures to the emergency services."