Search efforts at the crash site of a German jetliner in the French Alps were suspended late Tuesday, as night fell over mountainous terrain where officials say the lives of all 150 passengers and crew were lost earlier in the day.

About a dozen specially trained mountain police were guarding the site in southeastern France, as rescue teams prepared to begin retrieving bodies at daybreak Wednesday.

German Jet Crashes in Alps: 150 Feared Dead

French Prime Minister Manuel Valls said a helicopter landed near where the Germanwings aircraft crashed in southeastern France, but rescue workers found no survivors. A local official in the ski resort region said the plane had disintegrated, with the largest debris the size of a small car.

German Jet Crashes in Alps: 150 Feared Dead

There was no immediate explanation for the accident. But French officials said one of the plane's black boxes that records key flight information has been recovered from the wreckage and could provide clues.

German Jet Crashes in Alps: 150 Feared Dead

In Washington, the White House said there was no indication that the crash was linked to terrorism.

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

By Wednesday evening, France Interior Minister Bernard Cazeneuve said one of the plane's black box recorders had been found and would be examined immediately.

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 crash 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 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.

Germanwings said the plane started descending one minute after reaching its cruising height of 11,500 meters and continued losing altitude for eight minutes.

“The aircraft's contact with French radar, French air traffic controllers, ended at 10:53 a.m. at an altitude of about 6,000 feet. The plane then crashed,” Germanwings' Managing Director Thomas Winkelmann told a news conference.

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

French Civil Aviation spokesman Eric Heraud said the plane lost radio contact at 10:30 a.m. Tuesday, but “never declared a distress alert itself.” He said it was the combination of loss of radio contract with air traffic control and the plane's descent that prompted the control service to declare a distress.

Winkelmann said French air traffic controllers lost contact with the flight at an altitude of about 1,800 meters.

Capt. Benoit Zeisser of the Digne-le-Bains police said there were some clouds in the region at the time of the crash, but the cloud ceiling was not low and there did not appear to be turbulence.

In addition, the safest part of a flight is when the plane is at cruising elevation. Just 10 percent of fatal accidents occur at that point, according to a safety analysis by Boeing. In contrast, takeoff and the initial climb accounts for 14 percent of crashes and final approach and landing accounts for 47 percent.

French President Francois Hollande called the crash "a tragedy on our soil."

Hollande offered condolences to the families of the victims, and said he had established a crisis center to work with the Spanish and German governments, and the victims’ families.

He also called German Chancellor Angela Merkel to express his condolences.

Merkel's spokesman said she was "deeply shocked" by the accident and canceled all of her other appointments for the day. Merkel said she would visit the crash site Wednesday.

"I will travel there tomorrow to get my own impression and to speak with local officials," she told reporters.

Spanish Prime Minister Mariano Rajoy said in a Twitter message: "Shocked by the air accident in the Alps. A tragedy. We are cooperating with the French and German authorities in the investigation."