US aviation investigators have detailed how a broken engine part shattered a window on a Ryanair Boeing 737-800, partially pulling a passenger through the opening during a flight from Thessaloniki, Greece. The National Transportation Safety Board released its preliminary findings on Wednesday.

The flight, bound for Memmingen, Germany, was forced to turn back to Thessaloniki less than ten minutes after takeoff on July 10. A fan blade in the right engine broke loose, sending debris outward that shattered a cabin window and damaged the fuselage in several other spots, according to the NTSB report cited by CNN and other outlets.

Ryanair said at the time that the window dislodged in flight while the aircraft was over North Macedonia, prompting the crew to declare an emergency and return to Thessaloniki’s Macedonia Airport, where firefighters and ambulances were placed on standby. Four passengers were taken to hospital as a precaution, and most were examined and discharged the same day. Ryanair’s chief executive later said initial indications pointed to foreign object damage to the engine on takeoff.

The passenger in seat 11F, 61-year-old Ljubisa Karovic, had his head and shoulders pulled through the broken window before his wife and a flight attendant were able to pull him back inside. He suffered neck and shoulder injuries along with friction burns, according to the Washington Times and ClickOrlando.

Investigators found bird remains inside the damaged engine, raising the possibility that the aircraft struck birds during takeoff, though the NTSB has not yet determined what specifically caused the fan blade to fail. The report noted that the engine’s fan blades had been inspected less than three weeks earlier, under a rule put in place following a similar past incident.

The case echoes a 2018 accident involving a Southwest Airlines Boeing 737, in which a snapped fan blade shattered a window and partially pulled a passenger outside the aircraft. That passenger, Jennifer Riordan, later died of blunt force trauma, a tragedy that prompted tighter fan blade inspection rules across the industry.

Ryanair has not issued a new public statement since the preliminary report’s release. The NTSB investigation remains open, and a final report determining the root cause of the fan blade failure is expected at a later date.