French investigators cracked open the mangled black box of a German jetliner today and sealed off the rugged Alpine crash site where 150 people died when their plane slammed into a mountain. The dented, twisted and scarred cockpit voice recorder was being mined by investigators for clues into what sent the Germanwings Airbus 320 into a mid-flight dive yesterday after pilots lost radio contact over the southern French Alps during a routine flight from Barcelona to Duesseldorf. Germany's top security official said today there was no evidence of foul play. Helicopters surveying the scattered debris lifted off at daybreak to eye the craggy ravine. Emergency crews, meanwhile, traveled slowly over the steep, rocky terrain to the remote high-altitude crash site through fresh snow and rain. Bereaved families and the French, German and Spanish leaders were expected later today. "The black box is damaged and must be reconstituted in the coming hours in order to be useable," French Interior Minister Bernard Cazeneuve told RTL radio. Key to the investigation is what happened in the two minutes of 10:30 AM and 10:31 AM (local time), said Segolene Royal, a top government minister whose portfolio includes transport. From then on, air traffic controllers were unable to make contact with the plane. The voice recorder takes audio feeds from four microphones within the cockpit and records all the conversations between the pilots, air traffic controllers as well as any noises in the cockpit. France's air accident investigation agency released images of the orange casing, mangled and scarred from the impact. The flight data recorder, which Cazeneuve said has not been retrieved yet, captures 25 hours' worth of information on the position and condition of almost every major part in a plane. France's air force says it scrambled a Mirage fighter jet to the area when the flight lost radar contact, but arrived too late to help. German Interior Minister Thomas de Maiziere told reporters in Berlin today that "according to the latest information there is no hard evidence that the crash was intentionally brought about by third parties." Royal and Cazeneuve both emphasised that terrorism is considered unlikely. The crash left pieces of wreckage "so small and shiny they appear like patches of snow on the mountainside," said Pierre-Henry Brandet, the Interior Ministry spokesman, after flying over the debris field. Investigators retrieving data from the recorder will focus first "on the human voices, the conversations" followed by the cockpit sounds, Transport Secretary Alain Vidalies told Europe 1 radio. He said the government planned to release information gleaned from the black box as soon as it can be verified. Deborah Hersman, president and CEO of the National Safety Council and a former chair of the National Transportation Safety Board, said generally voice recorder data can be downloaded in a matter of hours. She told NBC's "Today" show that the data will offer insight into "those critical minutes and seconds leading up to the crash." "I'm absolutely confident that the investigators are going to figure out what happened," she said. Germanwings CEO Thomas Winkelmann said the company was already in contact with families of 123 victims and trying to reach relatives of the remaining 27. He said victims included 72 German citizens, 35 Spanish, two people each from Australia, Argentina, Iran, Venezuela and the US and one person each from Britain, the Netherlands, Colombia, Mexico, Japan, Denmark, Belgium and Israel. Some could have dual nationalities. They included two babies, two opera singers, an Australian mother and son vacationing together, and 16 German high school students and their two teachers returning from an exchange program in Spain. "Nothing will be the way it was at our school anymore," said Ulrich Wessel, the principal of Joseph Koenig High School in the German town of Haltern. "I was asked yesterday how many students there are at the high school in Haltern, and I said 1,283 without thinking then had to say afterward, unfortunately, 16 fewer since yesterday. And I find that so terrible," he added. In the French town of Seyne-les-Alpes, locals offered to host bereaved families because of a shortage of rooms to rent. The plane, operated by Germanwings, a budget subsidiary of Lufthansa, was less than an hour from landing in Duesseldorf when it unexpectedly went into a rapid eight-minute descent. The pilots sent out no distress call, France's aviation authority said. Lufthansa CEO Carsten Spohr, himself a pilot, said he found the crash of a plane piloted by two experienced captains "inexplicable."