A woman has died after her family was overcome by fumes in a tent.
A spokesman for North Wales Police said officers were called to a caravan site in Gyrn Goch, Caernarfon, at 9.29am on Monday to assist paramedics.
Police said "initial indications" were that the family of four, including two children, aged four and seven, had been "overcome by fumes within the tent".
The mother of the two children was declared dead at the scene, police said.
The two children and a man are receiving treatment in hospital and are in a comfortable condition.
A post-mortem examination will be taking place to confirm the cause of death but it is not being treated as suspicious by police.
Detective Sergeant Brian Kearney said: "We are grateful to the members of the public on the campsite who assisted by taking the children to safety."
The man was airlifted to Ysbyty Gwynedd hospital in Bangor, and the children were taken there by road. Police said they were in a comfortable condition.
It is understood they were staying in a family-owned tent at Aberafon Camping and Caravan site.
The site's website says the camp adjoins a private beach and there are 15 acres of valley grounds. It is at the foot of the 1,500ft Gyrn Goch and near the hamlet of the same name.