Crews have worked into the night to retrieve the bodies of a British father and his son after five members of the same family were caught in a landslip in NSW Blue Mountains.

The nine-year-old boy and his 49-year-old father died at the scene at Wentworth Pass, NSW Police said.

A 50-year-old woman and a 14-year-old boy were winched from the scene and taken to hospital in critical conditions with significant head and abdominal injuries following the land slip on the walking track.

A fifth member of the same family, a 15-year-old girl, was treated for shock after the incident, which was reported to emergency services at about 1.40pm (AEST) on Monday.

Police said the family are British nationals who were holidaying in Australia.

Detective Acting Superintendent John Nelson said: “Unfortunately there’s been a landslip while they’ve been bushwalking.

“It’s quite a tragic scene.”

He described the 15-year-old girl as “extremely distressed”.

“Both patients have significant head and abdominal injuries requiring sedation and intubation prior to them being extricated via winch,” NSW Ambulance Acting Chief Superintendent Stewart Clarke told media.

The incident happened in an “extremely dangerous, extremely unstable environment,” Clarke said, describing the situation as heartbreaking.

“It is terribly sad to have lost two lives here today and my heart goes out to the families and the survivors of this horrific ordeal who have witnessed what is certainly a traumatic event,” Mr Clarke said.

He described the rescue operation as “complex and delicate” with crews working hard to access patients in rugged bushland and on unstable ground.