Divers retrieved one black box on Monday and located the other from the AirAsia plane that crashed more than two weeks ago, a key development that will help investigators unravel what caused the aircraft to plummet into the Java Sea.

The cockpit voice recorder was found just hours after officials announced that the flight data recorder had been pulled from beneath a piece of the aircraft's wing and brought to the sea's surface, said Suryadi Bambang Supriyadi, operation coordinator for Indonesia's national search and rescue agency.

However, he said that the voice recorder remained lodged beneath heavy wreck-age, and divers were struggling to free it at a depth of 32 meters.