All options must be looked into to explain why a German Airbus ploughed into an Alpine mountainside on Tuesday but a terrorist attack is not the most likely scenario, French Interior Minister Bernard Cazeneuve told RTL radio this morning.

Cazeneuve confirmed that the black box that was found yesterday was the cockpit voice recorder, saying that it had been damaged but could still be used to find information.

Germanwings will have to cancel more flights on Wednesday as some crew members refuse to fly, a day after the Airbus A320 operated by the budget arm of Lufthansa  crashed in the French Alps ."There will be irregularities ... There are crew members who do not want to fly in the current situation, which we understand," a spokeswoman for Germanwings said.

Germanwings flight 4U 9525 from Barcelona to Duesseldorf crashed into a mountainside on Tuesday, killing all 150 people on board including 16 school children.

The airline believed there were 67 Germans on the flight. Spain's deputy prime minister said 45 passengers had Spanish names. One Belgian was 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.

Investigators described a scene of devastation where the airliner crashed.

"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," Bruce Robin, prosecutor for the city of Marseille, told Reuters in Seyne-les-Alpes after flying over the crash zone in a helicopter.

French police at the crash site said no one survived and it would take days to recover the bodies due to difficult terrain, snow and incoming storms.

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 told Reuters.

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 worldwide aviation fleets. They are the world's most used passenger jets and have a good though not unblemished safety record.