The National Transportation Safety Board said Thursday that Boeing will face sanctions after violating an agreement by disclosing details of an investigation into a Boeing 737 Max 9 door panel that exploded in midair, NBC News reports.

According to the agency in a briefing, Boeing "flagrantly violated NTSB investigative rules" by providing investigative information that was not authorized for publication and speculating about the cause of the nearly six-month-old incident.

The agency said an unidentified Boeing spokesman described improvements at Boeing's commercial airplane division on Tuesday, including "analyzing factual information released earlier."

Boeing also mischaracterized the investigation as an attempt to find the person responsible for installing the door stopper, the statement said.

That means Boeing violated the parties' agreement it signed at the start of the investigation, the agency said.

On Jan. 5, an Alaska Airlines flight had a door panel tear off while flying at 16,000 feet, about 10 minutes before its scheduled arrival time in Portland, Oregon.

The accident plunged Boeing into crisis and raised ongoing questions about the safety of flying other airplane models, which are now the subject of multiple federal investigations.