SHERIDAN, Wyo. (AP) — Federal investigators are trying to determine what caused a small twin-engine life flight aircraft to go off a taxiway and into a ravine at Sheridan County Airport.

Airport manager John Stopka says the plane owned by Exec Air of Helena, Mont., had dropped a patient off and was preparing to take off when it went off the side of the taxiway and into a ravine at about 5 p.m. Wednesday. The two people aboard were not injured.

Stopka tells The Sheridan Press (http://bit.ly/ugywXb ) the plane "is in a pretty deep hole, and it will take some effort to get it out of there."

The Federal Aviation Administration and the National Transportation Safety Board are investigating.

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