PARIS/SEYNE-LES-ALPES, France, March 25-- German Chancellor Angela Merkel and Spanish Prime Minister Mariano Rajoy on Wednesday thanked France for its efforts in the wake of the deadly plane crash in southern France on Tuesday.

The aircraft A320 operated by Lufthansa's budget airline Germanwings crashed in the southern French Alps while flying from Barcelona, Spain to Dusseldorf, Germany.

A total of 144 passengers and six crew members lost their lives.

French President Francois Hollande, Merkel and Rajoy arrived Wednesday afternoon in Seyne-Les-Alpes where a search and rescue operation station had been set up. They also went to Vernet to visit the chapels which offered families of the victims a place to mourn the loss of their loved ones.

According to French Interior Minister Bernard Cazeneuve who arrived on site after the crash on Tuesday, "an exceptional operation is underway," with 300 gendarmes, about 300 firemen, and volunteer firmen deployed.

Xavier Roy, coordinator of the search operation, told Xinhua Wednesday morning that the priority now was to find the second black box. Hollande confirmed Wednesday afternoon that "the outer shell of the second black box was found, but no sign of the black box."

A damaged black box, the plane's cockpit voice recorder, was retrieved on Tuesday, and was transported Wednesday morning to the Paris-based Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) to be analyzed.

The BEA managed to extract useful data from the damaged black box retrieved from the downed plane Wednesday afternoon.

Remi Jouty, general director of the BEA, said at a press conference in Paris that the file extracted from the damaged black box was an audio file.

The last message exchange between the cockpit and air traffic control was a routine message, Jouty revealed, adding that the last altitude of 4U9525 on the radar was about 1,829 meters.

"At this point, we are not in a position to give any explanation of the crash," affirmed the BEA chief, adding that the whole process of decryption and analysis of the black box could take weeks, even months.

He declined to comment on whether the voice from the audio file was of the pilots, saying BEA had only extracted the file and needed time to identify the voices.

The BEA said the tiny size of the debris corresponded to the situation where the aircraft hit a hard surface at a large angle, adding that if there had been an explosion in mid-air, the size of the debris would be larger.

Two Germanwings planes transporting the relatives of the victims as well as psychologists were expected to arrive in southern France on Thursday, with one flying from Dusseldorf and the other from Barcelona. The airline would also send an additional plane to take family members of the crew to France.

"We need to know what happened. We owe it to the families (of the victims), we owe it to the countries involved in this tragedy," said France's Hollande Wednesday afternoon in a joint press conference with Merkel and Rajoy, adding that the German and Spanish leaders could be sure "that everything will be known and explanations on the conditions of the catastrophe."

Merkel extended a "very big thank you...in the name of millions of Germans who appreciate (what France has done)."

"My thoughts are with the families and friends of the victims, but also with the French people, especially to the people living in the region who offer their help," the German Chancellor affirmed.

Rajoy also thanked the French people and French president for their committed efforts in the search operation.