Family trapped in Blue Mountains

A rescue operation is underway in the Blue Mountains after a family group of bushwalkers activated an emergency distress beacon.

The three adults and two children have been trapped in the vicinity of Mt Wilson since Thursday afternoon.

The group was found after a search by Police Rescue, a NSW Ambulance Service helicopter, with a Special Casualty Access Team (SCAT) on board, and the Rural Fire Service.

An eight-year-old boy in the group was found to be suffering from mild hypothermia and is being treated at the scene.

Police believe they did not take adequate supplies of food, water and warm clothing.

Further attempts to winch in more rescuers had to be cancelled due to the conditions. This required Police Rescue Squad members to trek to the group.

It is expected emergency services will remain with the bushwalkers overnight before trying to bring them out on Friday morning.

The group logged their trip with Katoomba Police and signed out an emergency distress beacon before setting off.