The Piper PA32 went down at 2:21 p.m. near the Fountain Run area of Barren County, according to to the Federal Aviation Administration, reported AP.
Witnesses say ambulances, firetrucks and the Barren County Coroner were at the scene.
WSMV reported that the plane and its passengers were headed toward Lake Cumberland Regional Airport in Somerset, Kentucky, about 80 miles away from the crash site.
Three of the passengers were pronounced dead at the scene, and the fourth passed away shortly after at the Medical Center in Bowling Green, said state police.
The victims have yet to be publicly identified and the cause of the crash is unconfirmed.
Kentucky State Police Public Information Officer Jeremy Hodges told WBKO that from initial inspection, it appeared that the plane hit some treetops before finally coming to a stop against some tree trunks.
Kentucky State Police had to cease their investigation with the fading daylight.
National Transportation Safety Board spokesman Terry Williams said investigators will continue the investigation at the site on Monday, according to AP.
Glasgow is 100 miles south of Louisville, Kentucky.
