A Germanwings passenger jet carrying at least 150 people has crashed in a remote part of the French Alps, with all on board feared killed.
The pilots sent out no distress call and had lost radio contact, France's aviation authority said, deepening the mystery over the A320's mid-flight crash following a steep descent lasting eight minutes as it travelled from Barcelona to Dusseldorf.
The plane crashed at an altitude of about 6,550 feet, at Meolans-Revels, near the popular ski resort of Pra Loup. The site is 430 miles south-south-east of Paris.
The crash left officials and families across Europe in shock, with sobbing relatives at both airports being helped by airport workers and crisis counsellors.
German chancellor Angela Merkel told reporters in Berlin: "We still don't know much beyond the bare information on the flight, and there should be no speculation on the cause of the crash.
"All that will be investigated thoroughly."
French interior minister Bernard Cazeneuve said a black box has been located at the crash site, though it is not immediately clear if it has been recovered yet.
In Washington, the White House said American officials were in contact with their French, Spanish and German counterparts.
"There is no indication of a nexus to terrorism at this time," said US national security council spokeswoman Bernadette Meehan.
Photos of crash site from the La Provence newspaper showed scattered black flecks across a mountain and several larger aeroplane body sections with windows, five in one chunk and four in another.
France's prime minister Manuel Valls said a helicopter crew that landed briefly in the area saw no signs of life.
Gilbert Sauvan, president of the general council at Alpes-de-Haute-Provence in south-west France, told reporters: "Everything is pulverised.
"The largest pieces of debris is the size of a small car. No-one can access the site from the ground."
Germanwings said Flight 9525 carried 144 passengers - including two babies - and six crew members.
Officials believe 67 German nationals were on board, including 16 high school students on an exchange programme from the German town of Haltern. Dutch officials said one Dutch citizen was killed.
The plane left Barcelona Airport at 10.01am local time, then began descending again shortly after it reached its cruising height of 38,000ft, Germanwings CEO Thomas Winkelmann said.
The descent lasted eight minutes, he told reporters in Cologne.
Eric Heraud of the French Civil Aviation Authority said the plane lost radio contact at 10.30am, but "never declared a distress alert itself".
He said the combination of a loss of radio contract and the plane's quick descent prompted the controllers to declare a distress situation.
Sandrine Boisse, the president of the Pra Loup tourism office, said: "It was a deafening noise. I thought it was an avalanche, although it sounded slightly different. It was short noise and lasted just a few seconds."
French interior ministry spokesman Pierre-Henry Brandet told BFM television he expected "an extremely long and extremely difficult" search and rescue operation because of the area's remoteness. The weather in the area deteriorated as the afternoon progressed, with a chilly rain falling.
Mr Winkelmann said the pilot, whom he did not name, had more than 10 years' experience working for Germanwings and its parent airline Lufthansa. Airbus said the A320 involved in the crash was delivered to Lufthansa in 1991.
"We cannot say at the moment why our colleague went into the descent, and so quickly and without previously consulting air traffic control," said Germanwings' director of flight operations, Stefan-Kenan Scheib.
The aircraft had approximately 58,300 flight hours in some 46,700 flights, Airbus said. The plane last underwent a routine check in Dusseldorf on Monday, and its last regular full check took place in the summer of 2013.
Germanwings is a lower-cost unit of Lufthansa, Germany's biggest airline, and serves mostly European destinations. It has been operating since 2002, part of traditional national carriers' response to competition from European budget airlines.
The municipal sports hall of Seyne-les-Alpes, six miles from the Val d'Allos ski resort, is being set up to take bodies from the crash.
Captain Benoit Zeisser of the nearby Digne-le-Bains police said there had been some clouds in the morning but the cloud ceiling was not low.
In a live briefing in Paris, French President Francois Hollande called the crash "a tragedy on our soil".
Ms Merkel spoke with both Mr Hollande and Spanish prime minister Mariano Rajoy about the crash, immediately cancelling all other appointments.
"The crash of the German plane with more than 140 people on board is a shock that plunges us in Germany, the French and the Spanish into deep sorrow," said Ms Merkel, who plans to travel to the region on Wednesday.
Worldwide, a total of 3,606 A320s are in operation, according to Airbus.
The A320 family also has a good safety record, with just 0.14 fatal accidents per million take-offs, according to a Boeing safety analysis.
A French interior ministry official later confirmed the black box has been recovered from the site.
An opera house in Dusseldorf has said bass baritone Oleg Bryjak was among the 150 people on board the plane.
The Deutsche Oper am Rhein said Bryjak was on his way back from Barcelona, where he had sung Alberich in Richard Wagner's Siegfried at the Gran Teatre del Liceu.
Director Christoph Meyer said: "We have lost a great performer and a great person in Oleg Bryjak. We are stunned."