Police are treating a forest fire in the foothills of the Mourne Mountains in County Down as suspicious.
More than 50 firefighters battled the blaze, which started in Donard Forest, on Sunday night into Monday morning.
The Northern Ireland Fire and Rescue Service (NIFRS) have determined it was likely the fire was started deliberately.
The fire front was a mile long and a total of eight appliances were at the scene.
"The fire caused widespread damage and led to a number of evacuations, including from a nearby caravan park," said Det Chief Insp Will Tate.
Police have appealed for witnesses to come forward.
The Newcastle Centre, a council-run leisure centre in the town, was opened for those evacuated.
More than 200 people were at the centre, according to the NIFRS, most of whom were staying at Bonny's Caravan Park.
Mats were set up in some of the rooms to allow for overnight stays.
Max Joyce of the NIFRS said the blaze was "substantial" when firefighters arrived at the scene on Sunday night.
"The fire was moving down towards the caravan park and we had 200 people evacuated, so I think that shows you the degree of severity," he said.
"At one stage we were concerned that the caravan park itself would be compromised with flames."
Mr Joyce said there was a "pattern of hill fires in and around Easter", some of which were started deliberately.
"If they set fire to a gorse and a mile away there's people's properties, or someone gets hurt, perhaps a child gets burned or one of the firefighters gets injured or worse..." he said.
"These people really need to stop doing this. I can't understand the mentality."
In Newcastle, residents of Tullybrannigan Road were also among those forced to leave their homes and several buses were brought in to help with the evacuation.
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.
Meanwhile, in the Republic of Ireland firefighters are trying to control a large gorse fire in west Donegal.