Official: 1 pilot apparently locked out of cockpit before Germanwings plane crashed

An official with knowledge of the audio recordings from the Germanwings flight that crashed in the Alps says one of the pilots apparently was locked out of the cockpit when the plane went down.

The official, who was not authorized to speak publicly about the investigation, said Thursday the details emerged from recordings recovered from the black box found among the debris of the aircraft.

The New York Times earlier quoted an unidentified investigator as saying someone can be heard knocking on the cockpit door. The Times quoted the source as saying: "And then he hits the door stronger and no answer. There is never an answer."

Lufthansa chief executive Carsten Spohr has said "two experienced and trained Lufthansa pilots" were aboard but gave no more information about them.