Stunned Ulster rally fans were today coming to terms with the death of champion driver Colin McRae in a horror helicopter crash at the weekend.

The popular 39-year-old former world champion was killed alongside his five-year-old son Johnny, friend Graeme Duncan, 37, and his son's six-year-old pal Ben Porcelli on Saturday.

All four died when the helicopter the rally legend was flying crashed and burst into flames at woods near his home in Lanark, Scotland.

Air accident investigators will today resume work at the site of the crash as they piece together exactly what happened. One theory is that the helicopter clipped trees while landing at about 4pm.

Up to 40 firefighters and an air ambulance were involved in Saturday's rescue operation. However, it is thought at least two people died at the scene.

A spokesman for Strathclyde police said the crash was not survivable and it had been difficult to tell the aircraft had been a helicopter.

A cordon was placed around the crash site area including a private road leading to the family home where McRae's wife Allison and young daughter Hollie were being comforted by family and friends. They are said to be shattered by their loss.

Colin McRae became Britain's first world rally champion when he took the title in 1995. He is the son of five times British rallying champion Jimmy McRae.

Hundreds of video Tributes have appeared on YouTube

Yesterday Mr McRae Snr described the accident as "unbelievable".

Speaking on behalf of the whole family, he said: "Colin was a great son, a loving husband to Alison and a fantastic father to Johnny and his big sister Hollie.

"Johnny was a great wee guy, spending every spare minute with his dad, and even at this early stage it looked like he had the potential to carry on the family dynasty.

"Our thoughts are also very much with the families of Ben Porcelli and Graeme Duncan.

"Ben was a great buddy of Johnny's and they had always spent a lot of time together both in and out of school. Graeme, who now resides in France, had been a close friend of Colin's since their schooldays and was back in Lanark on holiday.

"We are thankful for the overwhelming number of messages of support we have received from all around the world. Colin was very much an inspiration and role model to motorsport fans the world over."

Chief Superintendent Tim Love, Divisional Commander, South Lanarkshire Division, said: "We believe that the group were just returning from a visit to the nearby village of Quarter around 4.05pm yesterday when it appears the helicopter got into difficulty and crashed within the grounds of Mr McRae's family home."

Meanwhile Dave Richards (55), boss of Prodrive, which runs the Subaru entry in World Rally, miraculously escaped injury when his helicopter crashed yesterday. Mr Richards and his wife had been making their way home from the Belgian Grand Prix when their Eurocopter crashed at North Weald Airfield, Essex.

Both walked from the wreckage physically unharmed, but were treated for shock.