Investigators have been analyzing the flight data recorder from . Now, it seems we’re closer to an answer as to what happened on that tragic day. Data from the black box seems to indicate that the plane was purposefully put into a nose-dive, which would suggest thatthe crash was intentional.

On March 21, China Eastern Airlines Flight MU5735 departed Kunming at 1:11 p.m. local time bound for Guangzhou, due at 3:05 p.m. local time. The Boeing 737-800 never arrived. Videos posted to social media showed the aircraft plummeting to the ground in a near-vertical descent, killing all 132 people on board.

The crash raised one big question: What could cause an aircraft to essentially fall from the sky like that? Now, that the crash was likely the result of intentional action by someone on the flight deck.

The investigation has been a multinational operation, with officials from Boeing, the Federal Aviation Administration and the National Transportation Safety Board helping the Civil Aviation Administration of China figure out what happened on that day.

people familiar with a preliminary assessment done by U.S. officials. WSJ’s sources, who are not named, say that data from the plane’s flight data recorder suggest the plane entered a dive when someone pushed on the aircraft’s control columns. As one source told WSJ, “the plane did what it was told to do by someone in the cockpit.”

This conclusion appears to be backed up by Chinese authorities, who thus far have found no evidence of a mechanical problem with the aircraft. WSJ highlights the fact that the 737-800 is an incredibly popular aircraft type with a good safety record: As of 2018, this type of plane has been involved with just eight fatal accidents, out of more than 7,000 planes sold. (The aircraft involved in the China Eastern Airlines crash was a 737 Next Generation, a predecessor to .)

that neither Boeing nor U.S. regulators are currently working on bulletins or directives to warn airlines about a dangerous condition with this type of plane, further supporting the idea that the China Eastern Airlines crash was not the result of a mechanical failure.

Hypothetically, this could mean someone broke into the cockpit and forced the plane to dive, but when asked about this possibility by WSJ, China Eastern Airlines responded that such a scenario was not plausible. That means the investigation will likely turn towards the actions and motives of the pilots in the flight deck that day. The airline says both pilots were in good health and weren’t experiencing any apparent financial problems.

The investigation is still very much in its early stages, and a preliminary report has not yet been released to the public. As the investigation continues, officials may find evidence of a different possible cause, but as of now the data suggests that the aircraft may have been brought down intentionally by someone onboard.