From the AP one hour ago:
"One person close to the investigation, who was not permitted to speak to the media while the inquiry was under way, said Saturday that “some kind of explosion” might have occurred, because the floor above the cargo hold had been pushed up. Two oxygen bottles that supply the pilots are stored in that area.
Australian investigators, who got their first look inside the plane Saturday, discovered shards of an oxygen bottle throughout the cargo hold and in the floor above, which sits below the cabin, this person said. Officials cautioned that it was too soon to know if the oxygen canister had caused the damage, but theorized that it might have played a role, this person said.
“The dangerous goods manifest is going to be very closely inspected to see if there was anything that might have caused the oxygen bottles to explode,” the person said."