A huge operation is underway to rescue a man who fell and injured himself while caving two days ago.
At least eight teams - thought to be made up of more than 50 rescuers - have been called to the cave in the Brecon Beacons.
A spokesperson said the man fell in the Ogof Ffynnon Ddu cave system near Penwyllt, Powys on Saturday.
He then became trapped after hurting his back, and police were alerted - who called in internationally renowned specialists.
The caver suffered multiple fractures when a massive boulder fell on him inside the cave.
His rescue is taking a long time because he suffered suspected spinal injuries in the accident.
A source said the boulder came loose as he grabbed it with his hand on Saturday.
The caver, who has not been named, then fell several feet before the giant rock landed on top of him.
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Two A&E consultants, both keen cavers, are with the man hundreds of feet underground.
Rescuers are carrying him out by stretcher.
The source said they are now past the most dangerous phase, where they had to wade through waist-deep water.
But it could be midnight before the man, who is a regular visitor to the cave system, is finally brought to the surface.
His injuries include fractures to his clavicle, sternum, tibula, fibula, jaw and lacerations on his torso.
He is being given morphine to cope with the pain.
A rescuer, one of 242 taking part in the operation from across the UK, said: “He’s lucky to be alive.”
Rescuers said on Monday that that the casualty is being moved towards the top entrance of the cave, where he can exit.
The caving system is about 275m (902ft) at its deepest point and can only be accessed with a permit.
Pictures show groups of rescuers trekking through fields in the mist to access the caves.
The mission is being led by the South and Mid Wales Cave Rescue Team - who previously helped save 12 young Thai footballers and their coach from flooded caves in July 2018.
Seven other specialist teams have travelled from across the UK to join the rescue effort with equipment vans from across Britain.
A regular caver said: "It's a well known cave system, very popular with cavers and it is in the middle of a nature reserve.
"It's a really popular cave system, usually recommended for more experienced cavers rather than novices."
"This incident is ongoing and involves cave rescuers from teams across the UK," South and Mid Wales Cave Rescue Team said.
The caves were discovered by the South Wales Caving Club in 1946, according to Natural Resources Wales, with underground streams and waterfalls.
The name Ogof Ffynnon Ddu means Cave of the Black Spring.
The guide to the cave system is described as "classic in the UK, and its approximately 61km [31 miles] of passages provide everything from huge chambers, beautiful formations, to yawning chasms and thundering river passages.
"The routes though the cave are too numerous to mention."
It adds: "Be aware that the mainstream and some other parts of the cave are prone to flooding, and in any event a journey down the mainstream is long and cold and wet, so go prepared."
Involved in the mission are Gloucester Cave Rescue Group, Midlands Cave Rescue Organisation, Derbyshire Cave Rescue Organisation, Mendip Cave Rescue, South East Cave Rescue Organisation, Cave Rescue Organisation, and Upper Wharfedale Fell Rescue Association.
The South and Mid Wales Cave Rescue Team were called to use their specialist knowledge to help in the 2018 rescue from the flooded Tham Luang Nang Non cave when the Wild Boars junior football team became trapped.
The team members were underground for 18 days before being freed and the first voice they heard was Welsh caver John Volanthen.
The rescue team - a registered charity - was set up 1946 to support cavers exploring caves in the Swansea and Neath areas but expanded to cover emergencies across Wales.
They were also involved in the tragic search for missing schoolgirl April Jones.
