French Interior Minister Bernard Cazeneuve said on March 25 that a black box found among the debris of a Germanwings passenger jet that crashed in the Alps is the cockpit voice recorder.
Cazenueve said the box was damaged but still could be "useable" to learn information about what caused the A320 Airbus to slam into a mountainside on March 24, obliterating the aircraft and killing all 150 people on board.
He said investigators were not ruling out anything but he added there was no reason to suspect terrorism.
"All theories must be carefully examined until we have the results of the enquiry," Cazenueve said.
The minister said the enquiry "must start today."
Lufthansa, which operates the low-cost airline Germanwings, said it was acting under the assumption the crash was an accident.
Germanwings said the plane started descending one minute after reaching cruising height and continued losing altitude for eight minutes. It was not clear why.
Recovery teams have resumed work at the remote area where the plane crashed. Debris was reportedly scattered over a wide area.
Lufthansa CEO Carsten Spohr said footage of the crash site showing small pieces of debris "lets you deduce the energy with which the plane hit the ground."
"Seeing the site of the accident was harrowing," Spohr said on Twitter.
French police at the crash site about 2,000 meters above sea level said no one had survived and it would take days to recover the victims' remains due to difficult terrain, snow, and incoming storms.
One investigator who had visited the scene said, "The biggest body parts we identified are not bigger than a briefcase."
German Chancellor Angela Merkel, French President Francois Hollande, and Spanish Prime Minister Mariano Rajoy are due to visit the site on March 25.
Spain declared three days of mourning and was to hold a minute of silence at noon on March 25.
Germanwings believed 67 Germans had been on the flight. Spain's deputy prime minister said 45 passengers had Spanish names.
Spain declared three days of mourning and was to hold a minute of silence at noon on March 25.
Among the victims were 16 teenagers and two teachers from a high school in the town of Haltern am See in northwestern Germany.
They were on their way home after a weeklong exchange program near Barcelona, a reciprocal visit after 12 Spanish students spent a week at their school in December.
Students were sent home from the school after the crash on March 24, but many returned in the afternoon to mourn, holding candles and crying.
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.
Kazakhstan's Foreign Ministry said on March 25 that three Kazakh nationals -- Erbol Imankulov, 50; Aizhan Esenghalieva, 49; and Adil Imankulov, 25 -- were among the dead.
Lufthansa CEO Spohr said the company would " enable the relatives to grieve on site as soon as possible."
Germanwings was cancelling some flights on March 25 as some crew members had declared themselves unfit to fly.
"There are crew members who do not want to fly in the current situation, which we understand," a spokeswoman for Germanwings said.
The Alpine disaster was the first crash of a large passenger jet on French soil since the Concorde disaster just outside Paris nearly 15 years ago.
The pilots sent out no distress call and had lost radio contact with their control center, France's aviation authority said.