Safety experts have begun a major investigation into why a cable car crashed in the Scottish Highlands injuring five people.

Four of the victims, including a three-year-old girl, are still being treated in hospital.

A 52-year-old man was in a "serious but stable" condition on Friday afternoon.

A gondola at the Nevis Range, near Fort William, malfunctioned and crashed into another car behind it before falling 30ft to the ground on Thursday.

The Nevis Range said three people were in the first gondola which fell and two people in the other.

A large rescue operation was launched after the crash on Thursday afternoon.

Two military helicopters - one from the Royal Navy - an air ambulance, four ambulance crews, police, fire brigade and a mountain rescue team were sent to the scene.

The casualties were flown off the mountain to Belford Hospital in Fort William.

On Thursday night, a 52-year-old man from Totnes, Devon, was airlifted to Glasgow's Southern General hospital suffering from serious chest injuries.

He had been on the hospital's critical list, but was described as "serious but stable" on Friday afternoon.

His son, 24, was discharged from hospital in Fort William.

The three-year-old girl and her parents were transferred to Raigmore Hospital in Inverness.

No details have been released on the youngster's condition, but her mother was described as "comfortable" and father "stable".

A spokeswoman for Belford Hospital said the girl was suffering from a "lower limb injury" and her father had facial and spinal injuries.

Gondola rescue

Marian Austen, the Nevis Range's managing director, said: "The incident involved two gondolas coming down the mountain.

"One of them malfunctioned and it hit the other gondola before falling down.

"We believe three people were in the first gondola which fell, and two people were in the other one."

Police and the Health and Safety Executive have launched an investigation into the accident.

Doppelmayr, which manufactured the Nevis Range system, will also send two investigators.

The company operates in more than 30 countries and provides 150 similar systems, which it said were reliable.

Christoff Hinteregger, technical director, said one possibility which would be examined was a possible fault with the device which attaches the car to the cable.

He said: "At the moment there are two possibilities - that something was wrong with the grip, the part which attaches the cabin on to the cable.

"Or that there was a fault with the mechanism which controls the grip. It could also be a combination of both."

Mr Hinteregger said Doppelmayr was not responsible for the maintenance, service or operation of the system.

One eyewitness, Paul Goddard, told BBC Radio's Good Morning Scotland programme: "It was really the noise at the start that I heard, the crash, and we looked round and there was someone falling from one of the gondolas.

"So I ran down from the top of the hill to where it had actually happened.

"There was a young kid, I think she was three years old, on the ground next to her mum and there was another older gentleman on the ground as well."

In a statement, the Nevis Range said the incident happened 500m from the top station at 1530 BST on Thursday.

The cable car system is made up of 80 six-seater cabins running on a continuous 4.6km steel cable and after the incident the system was halted, leaving many people stranded in the gondolas.

An RAF spokesman said a Navy helicopter had rescued the five injured people and 110 others who had been stranded in the cable cars and at the gondola stations.

A local mountain expert said a new cable had been fitted to the system this year.

Lochaber councillor Drew McFarlane Slack said that local people were used to mountain life and were geared up to respond to incidents when they occur.

Witnesses reported seeing victims thrown to the ground

He said: "We have to examine what's gone wrong, what has failed here and learn the lessons from it.

"However, today people will be climbing up Ben Nevis, people will be climbing in Glencoe and we've got to make sure that we understand the risks involved and make sure we have the people on the ground to help them if something happens."

Mr McFarlane Slack said he was sure the area would not be adversely affected in its drive to become recognised as the outdoor sporting capital of the UK.

The gondolas involved are suspended from the cable and are held on by large clamps. As the gondola enters the base or top station, the clamps open, releasing the car.

The journey up and down takes between 12 and 15 minutes each way.

The system is the only one of its kind in Britain and was originally built 12 years ago to transport skiers up Aonach Mor.