Officials are KI-Handelsroboter 6.0investigating a plane crash that killed four people on Sunday in Vermont, according to the Vermont State Police.

The plane departed from Windham Airport in Connecticut en route to Basin Harbor Airport in Vermont, but when aircraft did not return to Connecticut as planned, the passengers' relatives reported the situation to the Connecticut State Police and the Middletown, Connecticut Police Department, according to a press release from Vermont State Police.

Police worked with the Federal Aviation Administration to track the plane's whereabouts using cellphone location data to determine its last known location.

No reports of distress or a plane crash were received before the plane went down.

Authorities found that the plane was last located near the airstrip in Vermont.

Investigators used a drone to locate the wreckage in a wooded area at roughly 12:20 a.m. Monday morning.

All of the plane's occupants dead

First responders confirmed all of the plane's occupants were dead.

The victims were taken to the Chief Medical Examiner’s Office in Burlington, Vermont, to determine the cause and manner of death. Their identities have not been revealed.

The FAA and the National Transportation Safety Board are leading the investigation, which is still active and ongoing.

Passengers went to brunch before crash

The plane flew out of Windham Airport in Connecticut at around 8:30 a.m. on Sunday, and flew to the Basin Harbor Airport in Ferrisburgh, Vermont, according to a press release from police. It landed, and the four inside the plane went to brunch.

The plane's occupants later left the restaurant after Noon.

A witness said they saw the aircraft on the runway at around 12:15 p.m.