A pair of Massachusetts residents and a Connecticut man were killed in a plane crash on the Greenfield-Leyden line Sunday afternoon, according to the Massachusetts State Police.

Identities of the three passengers killed in the crash were released on Monday. Indian Orchard resident William Hampton, 68, Southwick’s Fredrika Ballard, 53 and Woodstock, CT resident Chad Davidson, 29, were all aboard the twin-engine Beechcraft 55 Baron that crashed within the Leyden Wildlife Management Area on Sunday, officials said.

Ballard was the owner of Fly Lugu Flight School in Westfield and Hampton was a Fly Lugu flight instructor, according to officials. Davidson was a student pilot, police said.

The plane, owned by the Fly Lugu Flight School, departed from Barned Airport in Westfield almost an hour and a half before the plane was located, according to officials. Troopers on the scene confirmed that the three individuals killed were the plane’s only occupants.

The three victims were removed from the wreck by firefighters and transported to the Office of the Chief Medical Examiner.

Officials said the National Transportation Safety Board, Greenfield Police and the Northwest District Attorney’s Office are continuing to investigate the incident, with the NTSB leading the charge.

An NTSB representative said preliminary information on the incident is that the plane crashed under unknown circumstances near Leyden Wildlife Management Area. The NTSB investigator is expected to arrive at the scene Monday when the aircraft will be examined.

Information that will be gathered in the NTSB’s investigation includes fight track data, maintenance records, air traffic control communication records, possible surveillance video, witness statements, 72-hour background on the pilot and pilot’s license.