The Guardian- A vintage Swiss military plane, which was saved from being mothballed by a national fundraising campaign, has crashed into a mountain in the Alps, killing all 20 people onboard.

The JU-52 HB-HOT aircraft, which was constructed in 1939, was flying from Locarno, near Switzerland’s southern border, to airline JU-Air’s base in Dübendorf, a suburb of Zurich.

It crashed into the western peak of Piz Segnas, a 3,000-metre (10,000-ft) mountain above the resort of Flims, in the south-east of the country, shortly before 5pm (4pm BST) on Saturday, the impact occurring at 2,540 metres.

The victims – 11 men and nine women, aged from 42 to 84, including two pilots and a flight attendant – were all Swiss, apart from an Austrian couple and their son.

At a news conference in Flims on Sunday, Kurt Waldmeier, the chief executive of the airline, said: “Yesterday was the worst day in the 36-year history of JU-Air. We have all suffered a very great loss.”

Police said they were not aware of any distress call and had not yet determined the cause of the crash, which occurred hours after a family of four was killed when their small plane went down further west in the Alps.

Photos released by Graubünden canton police showed the crumpled wreckage of the plane lying on the mountain, with only the upside-down tail more or less intact. The crash occurred in an area popular with hikers and skiers that includes a glacier.

The plane was flying the passengers back from a two-day trip to Locarno. Authorities were informed of the crash 50 minutes after the aircraft had taken off from Locarno’s Magadino airfield. Five helicopters were deployed in a search and rescue mission.

Speaking at the news conference, Daniel Knecht of the Swiss Transportation Safety Investigation Board said the plane appeared to have hit the ground “nearly vertically at high speed”.

Knecht said that while the investigation into the cause was likely to be relatively complex, officials could essentially rule out a collision with another aircraft or obstacle (such as a wire) and there was no indication of foul play or that it lost parts or broke up before the crash. He said that the hot weather conditions gripping Europe did not contribute to the crash.

The plane was one of three JU-52s used by the Swiss air force for more than 40 years. When they were taken out of service, a campaign raised about 600,000 Swiss francs (£464,000), enabling the aircraft to be transferred to civilian use and JU-Air to be launched in 1982. Flights began the following year, although the HB-HOT did not begin civilian service until 1985.

In 2007, the HB-HOT was used for the Tom Cruise film Valkyrie, about the 1944 plot by German officers to kill Adolf Hitler. It was also used in the classic 1968 war film Where Eagles Dare.

JU-Air offers sightseeing, charter and adventure flights with volunteers, who are described as “very experienced and specially trained airline and military pilots”. By 2014, its fleet was carrying more than 14,000 passengers a year.

Waldmeier said the plane that crashed had undergone a maintenance inspection last month. The airline has suspended flights until further notice.

It was the first time the airline had experienced an accident that resulted in death or injury, Waldmeier added.

Nearly 5,000 JU-52 planes, a product of Germany’s Junkers, were manufactured between 1932 and 1952. The aircraft have three engines, one on the nose and one on each wing.

The Federal Office of Civil Aviation closed the airspace above the crash site and access to popular hiking trails in the surrounding area was also blocked