GENEVA, Aug. 5 (Xinhua) -- All 20 people aboard a vintage plane that crashed in the Swiss Alps on Saturday were killed, local police said Sunday.

Also on Saturday, Cantonal police in Nidwalden in the center of the country said that a light aircraft went down near the town of Hergiswil, bursting into flames on impact and killing a family of four onboard, shortly before 10 a.m.

The vintage plane went down on the western side of the Piz Segnas Mountain at an altitude of 2,540 meters with 17 passengers, two pilots, and a flight attendant onboard.

In the crash, "there is no longer any hope of finding anyone alive," Andreas Tobler, the cantonal police chief of the canton of Graubuenden, told journalists in Flims, the Swiss News Agency SDA-ATS, reported.

All of the passengers were Swiss, except for a couple from Austria also on board with their son, Swissinfo, the website of the national broadcaster reported.

The Swiss News Agency said the Junker Ju-52, which was constructed in 1939, was owned and operated by local airline JU-AIR, which specializes in sightseeing flights.

The cause of the crash is not known, said Daniel Knecht of the Swiss Transportation Safety Investigation Board.

He said, "The aircraft crashed almost vertically and at a relatively high speed."

The fatal flight was fully booked for the journey from the canton of Ticino near Italy in southern Switzerland over the Alps to Duebendorf in the canton of Zurich.

Salvage operations included the deployment of five helicopters and continued on Sunday morning with the airspace around the accident site closed.

Knecht said the vintage aircraft may not have had crash-resistant cockpit voice and data recorders that more modern aircraft have.

But he said that the age of the aircraft might not have had a bearing on the crash.

"Even older aircraft, if they are well maintained, can be safely operated," said Knecht, noting the plane that crashed had been serviced every 35 hours, most recently in July.

He said officials have ruled out a collision with another aircraft or hitting an obstacle such as a wire.

The two crashes Saturday come just a week after a light aircraft accident in canton Valais that claimed the lives of four people, Swissinfo reported.