A 15-year-old boy has died and a girl, 14, is fighting for her life after they fell into a quarry.
The incident took place near Limekiln Road in Abersychan, Torfaen, Wales on Wednesday evening.
Gwent Police said the boy, from Pontypool, sadly died at the scene.
The girl - who is in critical condition - is now being treated at the University Hospital of Wales in Cardiff, after a Coastguard helicopter was needed to rescue her.
The Welsh Ambulance Service said it received a 999 call at 6.30pm.
South Wales Fire and Rescue Service immediately sent two crews to the scene.
Further assistance was needed after Welsh Ambulance Service requested help from the HM Coastguard around 19:20, due to the nature of the terrain at the quarry.
A spokeswoman added that the coastguard helicopter had to winch down paramedics to rescue one of the casualties.
The 14-year-old girl was then flown to a Cardiff heliport before being taken by ambulance to the University Hospital.
Torfaen council is now working closely with the leadership team at the boy's school to provide support for everyone affected.
It added: "Our colleagues from the educational psychology service have been at the school since the start of the day and further support is also on hand from the school counselling service."
Meanwhile, speaking about the incident, one councillor said the accident would have reverberations throughout local communities.
Councillor Janet Jones, who represents Blaenavon, said: "This is a tragic incident, and the effects of it will have reverberations throughout the communities of Blaenavon and Abersychan.
"My thoughts are with the two families, and I'm sure the local community and the local community council will rally around to support them through this terrible time."
