More than 50 firefighters are battling to bring a blaze under control on the Mourne Mountains in County Down.
The Northern Ireland Fire and Rescue Service received a report that a fire had broken out in Donard Forest at 20:30 BST on Sunday.
The fire front is a mile long and efforts to bring it under control is expected to last into Monday morning.
A total of eight appliances are at the scene.
Guests at Bonny's Caravan Park near to where the fire is have been evacuated.
Residents of Tullybrannigan Road were also among those forced to leave their homes and several buses were brought in to help with the evacuation.
The Newcastle Centre, a Council-run leisure centre in the County Down town, was opened for people evacuated due to the fire.
It is understood at least 200 people are at the centre, most of whom were staying at Bonny's Caravan Park.
Mats were set up in some of the rooms to allow for overnight stays.
Jim Beattie, who was on Tullybrannigan Road when the fire broke out and has a caravan in Bonny's Caravan Park, said the fire had spread so quickly it was "unbelievable".
"It was at the edge of the house here when it diverted and there are at least five fire crews here that I can see and they are starting to evacuate the homes," he said.
"We don't know where people are being told to go.
"There is no sense of panic but residents are naturally concerned and haven't been told where to go, simply to get out. It is really raging now."