France's transport minister said there were "no survivors" from the crash of the Germanwings Airbus A320.
"The circumstances of the accident, that are not yet clear, make us think there are not thought to be any survivors," President Francois Hollande told reporters.
The plane was travelling from the Spanish coastal city of Barcelona to the German city of Duesseldorf when it went down in the Barcelonnette area in southeastern France.
The airliner, which was carrying 142 passengers and six crew, issued a distress call at 10:47 am (0947 GMT), civil aviation authorities said.
"The debris of a passenger plane has been found in the region of Barcelonette," said interior ministry spokesman Pierre-Henry Brandet.
He said "major rescue efforts" had been mobilzed.
The plane belonged to Germanwings, a low-cost affiliate of German airline Lufthansa based in Cologne which had no fatal accidents.
The single-aisle A320 typically seats 150 to 180 people.
Plane with 148 on Board Crashes in French Alps
Source: AFP