A Germanwings plane carrying 150 people has crashed in the French Alps on its way from Barcelona to Duesseldorf.

The Airbus A320 - flight 4U 9525 - went down between Digne and Barcelonnette. There are no survivors, officials say.

The "black box" flight recorder has been found, France's interior minister says. The cause of the crash is not known and the plane sent no distress signal during an eight-minute descent.

Among the passengers were 16 German pupils returning from an exchange trip.

Germanwings, a low-cost airline owned by Germany's main carrier Lufthansa, has an excellent safety record. French, Spanish and German leaders have expressed shock.

"This is the hour in which we all feel deep sorrow," German Chancellor Angela Merkel told reporters, adding that she was planning to travel to the crash site.

A recovery team reached the site, in a remote mountain ravine, earlier on Tuesday. Their work was called off in the evening and will resume at first light on Wednesday, the French interior ministry said.

Bruce Robin, a prosecutor from Marseille, told the Reuters news agency that he had seen the wreckage of the aircraft from a helicopter.

"The body of the plane is in a state of destruction, there is not one intact piece of wing or fuselage," he said.

German Foreign Minister Frank-Walter Steinmeier was also flown over the crash site and described it as "a picture of horror", the Associated Press news agency says.

Officials believe 67 of those aboard the plane were German citizens. Forty-five of the passengers had Spanish names, Spain's deputy prime minister said. The passengers included a German school class on its way back from an exchange trip as well as two opera singers, Maria Radner and Oleg Bryjak.

Ms Radner was travelling with her husband and baby.

Sandrine Boisse, a tourism official from the ski resort of Pra Loup, told the BBC that she had heard a strange noise in the mountains at around 11:00 (10:00 GMT).

"At first we thought it was on the ski slopes, an avalanche, but it wasn't the same noise," she said. "I think it was the noise of when a plane goes very quickly down."

The plane began descending one minute after it reached its cruising height and continued to lose altitude for eight minutes, Germanwings managing director Thomas Winkelmann told reporters.

He said the aircraft lost contact with French air traffic controllers at 10:53 at an altitude of about 6,000 feet.

The plane did not send out a distress signal, officials said. Earlier reports of a distress call, quoting the French interior ministry, referred to a message from controllers on the ground.

The White House has said there is no evidence so far of a terror attack. A Lufthansa official said they were assuming for the time being that the crash had been caused by an accident.

The Airbus A320 is a single-aisle passenger jet popular for short- and medium-haul flights.