Investigators say they have retrieved “usable information” from the heavily-damaged black box of the Germanwings flight which crashed into the French Alps.
French air crash investigation agency BEA chief Remi Jouty said investigators had retrieved cockpit voice recordings from the doomed flight, but said a full interpretation would take days.
“We have just succeeded in extracting usable data from the cockpit voice recorder,” Mr Jouty said on Wednesday.
“We have not yet been able to study and to establish an exact timing for all the sounds and words heard on this file.
“At this stage, we don’t have the slightest explanation or interpretation as to what led this plane to fly down.”
He said an investigation would take “a matter of days” and could be subject to errors.
French Interior Minister Bernard Cazeneuve said the black box had been heavily damaged, and said laboratories outside Paris were working hard to establish how the flight carrying 150 people crashed.
Mr Cazeneuve said a terrorist attack was not the main theory being investigated, but Mr Jouty said no theory at this point could be excluded.
The development comes as search teams confirmed they had found the casing of the second black box, but the recorder itself was still missing.
French President Francois Hollande, German Chancellor Angela Merkel and Spanish Prime Minister Mariano Rajoy visited the crash site to thank rescue workers.
Seventy-two Germans and 51 Spaniards were among those killed in the disaster.
Two Australians were also killed.
Speaking at the scene north of Nice, Mr Hollande promised Ms Merkel and Mr Rajoy investigators would get to the bottom of the mystery.
“Dear Angela, dear Mariano, rest assured… we will find out everything,” he said.
“France stands by you.”