A patient at the University of Vermont Medical Center is in critical condition after surviving a six-story fall at the hospital.

Hospital officials aren’t releasing any info about the patient’s identity or the specifics of injuries, but say they think they know how the fall happened.

Spokesperson Annie Mackin says the patient fell from the sixth floor of a stairwell that’s used by hospital employees and not patients.

Based on their investigation so far, staff believes the patient opened a window inside that stairwell and exited it on their own.

“This was an extremely distressing situation for everyone involved. I am grateful for the teams who provided lifesaving care,” said Dr. Stephen Leffler, the medical center’s president and chief operating officer.