Police in southeastern Graubuenden canton (state) said a several-seater plane crashed Saturday on the Piz Segnas mountain above the Swiss Alpine resort of Flims, striking the mountain's western flank about 8,330 feet above sea level.
A vintage plane's crash in Switzerland on Saturday killed all 20 people on board, Grisons cantonal police said on Sunday.
According to JU-AIR, a Ju-52 airplane, which seats 17 passengers along with two pilots, had crashed.
The victims were 11 men and nine women between the ages of 42 and 84- seven couples from various parts of Switzerland, a couple from neighboring Austria and their son, and the three crew members.
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The Junker JU52 HB-HOT aircraft was built in Germany in 1939 and is now a collectors' item.
Police said that the aircraft had burned and officials haven't yet been able to ascertain the exact number and identity of those who died.
"Based on the situation at the crash site we can say that the aircraft smashed into ground nearly vertically at relatively high speed", said Daniel Knecht of the Swiss Transportation Safety Investigation Board.
Knecht said officials expect the investigation of the cause to be "relatively complex, because we have to compare various indications, information and evidence and evaluate them".
"The plane turned 180 degrees to the south and fell to the ground like a stone", the witness said, adding that the debris was scattered over "a very small area" - indicating that an explosion was unlikely to have been the cause of the crash.
"What we can rule out at this point is that there had been a collision before the crash, neither with another aircraft nor with some other obstacle such as a cable".
Junkers JU-52 planes were manufactured between the 1930s and 1950s.
The aircraft belongs to JU-Air, a company with links to the Swiss air force, the ATS news agency reported.
In another crash over the weekend, a family of four including two young children were killed when a small plane came down in central Switzerland.