Chinese authorities said the pilot who died after crashing a small plane into Beijing’s tallest building was a 66-year-old man surnamed Liu, who reportedly deviated from his approved flight path before losing contact with air traffic control.

Officials said the crash was due to “personal reasons,” noting that Liu had a history of insomnia, anxiety, and writings expressing suicidal thoughts.

The incident has fueled public speculation because the aircraft entered highly restricted airspace near key government facilities despite China’s strict aviation controls.

Authorities have removed online discussions of the crash while investigating how the plane breached security measures, NBC News has reported.

The rare incident has raised questions about airspace oversight, as private flights in China require advance approval and are generally prohibited from flying over urban areas.