A helicopter ambulance flipped onto its side while landing at a airport in Alabama.

The Survival Flight helicopter wasn’t carrying any patients when it flipped during the Christmas evening landing, The Dothan Eagle reported.

The pilot was hospitalized after the crash at Headland Municipal Airport and two other crew members escaped serious injury, Headland police Chief Mark Jones said.

The pilot, 61-year-old Douglas Davis, later died. Henry County Coroner Derek Wright told WTVY-TV that Davis most likely suffered a heart attack. An autopsy is pending.

Jones said the helicopter was about 30 feet (9 meters) from the landing pad when it crashed. He said the troubled landing may have been caused by a medical issue.

Authorities didn’t immediately release the identities of the other crew members.

The extent of their injuries is unclear.

A man reached by the newspaper at the corporate office for Survival Flight identified himself as “Graham” and hung up after telling the newspaper “we’re not answering any questions at this time.”