Rally champion Colin McRae, his five-year-old son, a six-year-old boy and a family friend have been killed in a helicopter crash.
Strathclyde Police released the names of the four people they thought were on board the crashed aircraft on Saturday.
Mr McRae, 39, his son Johnny, the youngster's friend Ben Porcelli and family friend Graeme Duncan, 37, were all thought to be on board.
Formal identification is expected in the next few days.
Ch Supt Tim Love from Strathclyde Police said the crash was not survivable and it was very difficult to tell the aircraft had been a helicopter.
He added that the families have been shattered by the news.
Air accident investigators have started searching the helicopter crash site near Mr McRae's home in Lanarkshire on Saturday.
The Scottish Subaru Imprezza Owners' Club have been leaving tributes at the entrance to the house.
About 40 firefighters attended the accident which happened in woods just north of Lanark at 1600 BST.
Users of the rally champion's official website www.colinmcrae.com were greeted by a black screen on Sunday with no information available.
Police have been at the scene throughout the night and a cordon has been thrown around the area, including a private road up to the McRae family home.
Mr McRae, who is married with two young children, was Britain's first rally world champion in 1995 and is the son of five times British rallying champion Jimmy McRae.
Mr McRae admitted to enjoying the adrenaline rush of activities such as bungee jumping and was a keen pilot.
Nicky Grist, his co-driver since 1997, said: "Colin was always regarded as being a bit of a risk-taker in cars, but when it came to flying a helicopter he was a totally different man.
"The one thing he always told me, he said 'You don't mess about with a helicopter. They are bigger and better than I am and you have to drive them as such."
Mr McRae moved to the principality of Monaco in 1995, partly through his friendship with David Coulthard.
Fans have been laying tributes near Mr McRae's house
But as his family grew up, he spent more time back at his home in Lanarkshire. He and his wife Alison bought the 17th century Jerviswood House.
Rev Bryan Kerr, minister of Lanark Greyfriars Church and a neighbour of the McRae family, said: "A lot of people have been stunned by this and our thoughts go out to all of the families affected.
"This will be hugely devastating, particularly in such a small community. You just don't expect these things to happen on your doorstep especially when it is someone who is so well known and well liked in the town.
"The town's ministers have spoken to each other and special prayers will be offered for all those affected by the tragedy and remembering those who are working on the rescue efforts and trying to piece together what happened."
First Minister Alex Salmond said: "Colin McRae was an outstanding Scottish sportsman of international stature and achievement.
"His death is a great tragedy, and my thoughts and condolences are with all the families and friends bereaved by this terrible accident."
His brother, Alister, is also a professional rally driver and has enjoyed some success, including winning the British Rally Championship in 1995.
Mr McRae's sister is a doctor at the University Hospital in County Durham and she too enjoys rally driving.
The crash happened near the rally champion's home
He also achieved wider fame by endorsing a range of successful video games. Codemasters released the first Colin McRae Rally title in 1998.
'Colin McRae: DiRT' was the title for the latest instalment of the games series which launched this year on PC, Xbox 360 and PlayStation 3.
Stars from the world of motorsport have been paying tribute to Mr McRae.
Fellow Scot and Formula One ace David Coulthard, said: "He and Alison were good friends and I cannot imagine either without the other.
"He was fearless, flamboyant, blindingly quick in the car.
"We had some great times and his passing is a terrible blow for the McRae family and everyone who came in contact with him."