Two hikers have been taken to hospital after they were rescued by a Coastguard helicopter from the Mourne mountains in County Down on Saturday night.
They were part of a group of four men who were descending Slieve Bearnagh at about 16:30 BST.
One of the men had fallen near granite slabs on the mountain and suffered head and back injuries, and a second man was hurt while he tried to help.
A Coastguard helicopter took the men to Belfast for hospital treatment.
'Fallen some distance'
The Mourne Mountain Rescue Team (MMRT) had responded to the group's call for help, and 18 volunteers assisted with the rescue.
The HM Coastguard helicopter from Holyhead in Wales was called for the first faller "due to the severity the casualties injuries", the MMRT said.
An Irish Coast Guard helicopter then flew to the Mournes from Dublin for the second man when his condition deteriorated as he was being taken from the mountain.
Neville Watson, who co-ordinated the rescue for the MMRT, said the first man had become disorientated and had then "fallen some distance".
"The young guy who took the initial fall had stumbled - on that kind of steep ground once a fall starts it's very difficult to control it," he said.
'Steep, rocky area'
"The second guy had taken a tumble when he went down to see if his friend was OK.
"He was suffering from pain in his hip area and leg area and we were concerned that there may have been additional internal injuries along with that."
Mr Watson said the part of the mountain where the men, believed to be in their 20s, fell was a "fairly steep, rocky area", which is popular with rock-climbers.
"Unfortunately they found themselves on difficult ground and they really weren't up for that kind of terrain.
"There's also an element of bad luck."