Update: No distress call from pilots of downed German passenger jet, which 'disintegrated' in French Alps after suddenly plunging at 'catastrophic speed'

© Unknown

An aerial photo shows what appears to be wreckage from the crash of a Germanwings plane in the French Alps, between Barcelonnette and Digne.

A rescue helicopter has landed at the site of the Germanwings air disaster in the French Alps to find the plane "" and no survivors.

The Airbus A320 with 150 people on board came down in a mountainous region, at an altitude of around 6,500ft, between Barcelonnette and Digne.

After taking off at 9.55am (8.55am UK time), a distress signal was issued for flight 4U 9525 at 10.47am (9.47am UK time) after it found itself in an "" on its route from Barcelona to Dusseldorf.

France's Prime Minister Manuel Valls said a helicopter had managed to land near the crash site but found no survivors.

Gilbert Sauvan, of the local council, told newspaper: "."

France's President Francois Hollande said: "It's a tragedy on our soil."

Spain's Deputy Prime Minister, Soraya Sáenz de Santamaría, said 45 of those on board are thought to be Spanish. Germanwings said there were 67 Germans on board.

German Chancellor Angela Merkel was "deeply shaken" by news of the crash, her spokesman said.

French Interior Ministry spokesman Pierre-Henry Brandet said debris from the crash had been found at an altitude of 2,000 metres.

He added that he expected "" search and rescue operation because of the area's remoteness.

Emergency workers were not expected to reach the scene for several hours.

Eric Ciotti, the head of the regional council, said search-and-rescue teams were on the way to the crash site at Meolans-Revels.

Flight-tracking data indicated the aircraft plummeted from 40,000ft to 6,200ft in less than eight minutes before it crashed.

French aviation authorities said that the plane, operated by Lufthansa's budget airline, did not issue a distress call and that air traffic controllers had raised the alarm.

Aviation journalist Anthony Davis said: "The log suggests it went straight down at a significant rate, up to 5,000 feet per minute at one point, which suggests it happened in a matter of seconds.

© AFP

A helicopter of the French civil security services flies near Seyne, south-eastern France, on March 24, 2015, near the site where a Germanwings Airbus A320 crashed in the French Alps.

"the pilots did not send a typical distress call, a squawk of 770.

""

A total of 144 passengers, two pilots and four cabin crew were on board the 24-year-old plane. A spokeswoman for the German town of Haltern said there was reason to believe the passengers included 16 pupils and two teachers from one school .

Two babies were also among the passengers.

Germanwings chief executive Thomas Winkelmann told a news conference the pilot had more than 10 years experience, including more than 6,000 flight hours on A320s.

He said the firm would do everything possible to establish the cause of the crash.

The owner of a campground near the crash site, Pierre Polizzi, said he heard the aircraft making strange noises just before it crashed.

"I heard a series of loud noises in the air," he said.

".

"The noise I heard was long - like eight seconds - as if the plane was going more slowly than a military plane speed. There was another long noise after about 30 seconds."

Weather conditions were calm at the time the plane came down and Mr Valls said the causes of the crash were not yet known.

He said he had activated the ministerial crisis cell to help coordinate the aftermath of the crash. He added that he had sent Interior Minister Bernard Cazeneuve to the site.

Reports suggest debris at the crash site is not scattered, indicating there had been no mid-air explosion, and US officials say they do not believe terrorism was involved.

Lufthansa wrote on its Twitter page: "

"."

© ANNE-CHRISTINE POUJOULAT/AFP/Getty Images

A recovery operation is mounted near Seyne, south-eastern France, near the Germanwings crash site.

German foreign minister Frank-Walter Steinmeier said in a tweet: "."

Captain Mike Vivian, former Head of Flight Operations at the Civil Aviation Authority, told Sky News the A320 had a relatively good safety record.

"," he said.

"

"nobody goes low in the Alps unless you are landing at Zurich or Geneva.

"."