An Airbus operated by Lufthansa's Germanwings budget airline crashed into a mountainside in the French Alps today, killing all 150 people on board, including 16 schoolchildren.

Germanwings confirmed its flight 4U 9525 from Barcelona to Duesseldorf went down with 144 passengers and six crew on board.

One of the plane's black box recorders has been found at the crash site, about 100km north of Nice, and will be examined immediately, France's interior minister said.

Lufthansa said it was working on the assumption that the tragedy had been an accident, adding that any other theory would be speculation.

Aerial photographs showed smouldering wreckage and a piece of the fuselage with six windows strewn across the steep mountainside.

"We saw an aircraft that had literally been ripped apart, the bodies are in a state of destruction, there is not one intact piece of wing or fuselage," Brice Robin, prosecutor for the city of Marseille, told Reuters after flying over the wreckage in a helicopter.

Germanwings believed 67 Germans had been on the flight.

Spain's deputy prime minister said 45 passengers had Spanish names. One Belgian was also aboard.

Also among the victims were 16 children and two teachers from the Joseph-Koenig-Gymnasium high school in the town of Haltern am See in northwest Germany, a spokeswoman said.

Barcelona's Liceu opera house said on Twitter that two singers, Kazakhstan-born Oleg Bryjak and German Maria Radner, had died while returning to Duesseldorf after they had performed in Wagner's Siegfried at the theatre.

French police at the crash site about 2,000m above sea level said no one had survived and it would take days to recover the bodies due to difficult terrain, snow and incoming storms.

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Police said search teams would stay overnight at altitude.

"We are still searching. It's unlikely any bodies will be airlifted until Wednesday," regional police chief David Galtier said.

In Paris, Prime Minister Manuel Valls told parliament: "A helicopter managed to land [by the crash site] and has confirmed that unfortunately there were no survivors."

It was the first crash of a large passenger jet on French soil since the Concorde disaster just outside Paris nearly 15 years ago.

The A320 is a workhorse of aviation fleets and one of the world's most used passenger jets.

It has a good safety record.

However, according to data from the Aviation Safety Network, today’s crash was the third most deadly involving an A320.

In 2007 a TAM Linhas Aereas A320 shot off a runway in Brazil, killing 187 people, while 162 people died when an Indonesia AirAsia jet went down in the Java Sea in December.

Germanwings said the plane started descending one minute after reaching its cruising height and continued losing altitude for eight minutes.

"The aircraft's contact with French radar, French air traffic controllers, ended at 10.53am at an altitude of about 6,000 feet. The plane then crashed," Germanwings' Managing Director Thomas Winkelmann told a news conference.

Mr Winkelmann also said that routine maintenance of the aircraft was performed by Lufthansa yesterday.

Experts said that while the Airbus had descended rapidly, its rate of descent did not suggest it had simply fallen out of the sky.

France's DGAC aviation authority said air traffic controllers initiated distress procedures after they lost contact with the Airbus.

"The aircraft did not itself make a distress call but it was the combination of the loss of radio contact and the aircraft's descent which led the controller to implement the distress phase," a DGAC spokesman said.

In emergencies, pilots are trained to try to fly the aircraft as their first priority, then pay attention to navigation and only then communicate with the ground.

The aircraft came down in an alpine region known for skiing, hiking and rafting, but which is hard for rescue services to reach.

The search and recovery effort based itself in a gymnasium in the village of Seyne-les-Alpes, which has a small private aerodrome nearby.

As helicopters and emergency vehicles assembled, the weather was reported to be closing in.

"There will be a lot of cloud cover this afternoon, with local storms, snow above 1,800 metres and relatively low clouds. That will not help the helicopters in their work," an official from the local weather centre said.

Lufthansa Chief Executive Carsten Spohr, who planned to go to the crash site, spoke of a "dark day for Lufthansa".

"My deepest sympathy goes to the families and friends of our passengers and crew," Lufthansa said on Twitter, citing Mr Spohr.

German Chancellor Angela Merkel said she would travel to the site tomorrow. Germanwings and the Catalan regional government were preparing to take Spanish relatives there.

Family members arrived at Barcelona's El Prat airport, many crying and with arms around each others' shoulders, accompanied by police and airport staff.

In Llinars del Valles, the Spanish village that hosted the German schoolchildren, Mayor Marti Pujol said the whole village was distraught.

"The families knew each other," he said.

"The parents had been to see them off at six this morning."

King Felipe and Queen Letizia of Spain called off a state visit to France in a sign of mourning for the victims.

They had arrived in Paris minutes after the crash happened.

Airbus confirmed that the plane was 24 years old, having first been delivered to Lufthansa in 1991. It was powered by engines made by CFM International, a joint venture between General Electric and France's Safran.

Department aware of a plane crash in the Alps. No information as yet on the nationalities involved. Any concerns please ring at 01 4780822. — DFATravel (@dfatravel) March 24, 2015