Seventy army cadets from England have been rescued from the Mournes with some of them suffering from hypothermia and lower leg injuries.
An army spokesman said the cadets were all from England and are all now recovered from the mountains and being medically assessed.
They had gone rambling in the Mournes today but the rain “did not ease up” he said.
“There have been a handful of ankle injuries and some are suffering a little bit from the cold,” he added.
“Because it was a large group a huge support operation kicked in, for which we are very grateful.”
The Coastguard said that over 70 young people were in difficulties.
A spokesman told the News Letter that a smaller sub-group of 17 to 20 young people suffered “serious hypothermia and lower leg injuries”.
Three Coastguard helicopters, three Coastguard rescue teams, police and ambulances were involved, he said.
There were up to 70 young people involved, in a single group, although some of them became separated from the others, he said.
The Ambulance Service said it was called at 11:13am following reports of a group of young cadets requiring medical attention.
“Sixteen of the group are suffering from hypothermia and some with minor injuries,” a spokeswoman said.
The Ambulance Service declared a major incident at 1:21pm she added.
A Rapid Response Vehicle, 5 Officers, a Doctor, 10 A&E crews, a Hazardous Area Response Team and Mountain Rescue are in attendance at the scene.
An A&E crew have set up at Annalong Community Hall to treat the walking wounded.
Mourne Councillor Henry Reilly said around ten ambulances were waiting at the Head Road near Annalong.
One woman said on Facebook: “I was coming over the mountain from Rathfriland at approx 11 am and weather was wild. Rain and wind and flooding on the roads. Car got buffed about it was so bad.”
Another poster said two helicopters landed at Annalong harbour.
Mr Reilly said helicopters from North Wales, Ayrshire and Dublin were involved.