Rescuers have found a number of the 24 children who went missing the Brecon Beacons.
Dyfed-Powys Police said a Coastguard helicopter had found some the children, who are from St Albans, Hertfordshire.
The helicopter has landed and the crew are with the children, but their condition is not known.
The alarm was raised at about 13:00 BST after the groups went missing around Llyn y Fan Fach, near Abercraf.
The children are in their mid teens and were on the beacons as part of their Duke of Edinburgh Award.
Mark Moran from Central Beacons Mountain Rescue said his team had been in intermittent phone contact with the four groups of six children before the first group were found.
They were not accompanied by an adult and although rescuers knew the area the children were in, they were lost in the clouds.
The Welsh Ambulance Service has sent an ambulance, the Hazardous Area Response Team and the special operations response team to the scene.