One of the two pilots on the Germanwings flight was locked out of the cockpit before the plane crashed in the French Alps, killing 150 people, a source close to the investigation has told the AFP agency.
The New York Times also cited a senior military official involved in the investigation as saying the black box data indicated one pilot was locked out of the cockpit and tried unsuccessfully to bash his way back in.
"The guy outside is knocking lightly on the door, and there is no answer," the investigator told the newspaper. "And then he hits the door stronger, and no answer. There is never an answer."