Portland’s most senior firefighter has died in an apparent off-duty boating accident in Casco Bay.

Rescuers with the Portland Fire Department and U.S. Coast Guard were called to the area of Cushing Island at 12:40 p.m. Friday on a report of an unmanned vessel.

They found Timothy Flynn in the water about 500 feet from his boat. Fire officials say efforts to revive Flynn were unsuccessful.

The 58-year-old Flynn had been with the Portland Fire Department since 1986 and spent years serving on Ladder Co. 1 out of the Munjoy Hill Station.

Later he became pilot of the department’s Marine 1 vessel, a post he held until his death.