Members of the 126th Air Refueling Wing, Illinois National Guard, bow their heads during a prayer in front of a memorial at Scott AFB, Ill., on March 19, 2012, during a ceremony held to commemorate the four wing aircrew members who perished in an aircraft accident. | Photo: Master Sgt. Ken Stephens / National Guard

40 years ago today, an Illinois National Guard plane exploded mid-air and crashed in McHenry County, killing all 27 military personnel on board.

A KC-135A Stratotanker, assigned to the 126th Air Refueling Wing (AREFW), departed from northern Michigan en route to O’Hare Airport on March 19, 1982.

The aircraft was 40 miles northwest of O’Hare and had just been cleared for descent when an explosion caused the aircraft to disintegrate.

The plane’s fuselage broke apart and all four engines separated.

The remains of the plane, which was 13,000 feet in the air, crashed down into an open field in McHenry County near Greenwood.

The four crew members on board were assigned to the 126th AREFW, while the 23 passengers were members of the 928th Tactical Airlift Group (TAG).

A memorial was dedicated to four 126th Air Refueling Wing aircrew members who were among 27 to die in an aircraft accident on March 19, 1982. | Photo: Master Sgt. Ken Stephens / National Guard

All 27 members were killed in the incident. The last body was recovered two days after the incident.

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There were no injuries to people on the ground as a result of the crash and no serious damage to property.

The cause of the crash was undetermined but an investigative report said the most probable cause for the explosion was an over-pressurization under the cargo floor.

The 126th Air Refueling Wing on Friday published a video on social media to remember the members killed in the crash.

A Day of Remembrance event was held Saturday at the Wonder Lake Fire Department.

The name of each service member lost in the crash was read during the event.