DENVER — The Federal Aviation Administration is investigating after an air traffic controller was accused of ignoring a request for an emergency landing after a commercial airline pilot reported smoke in the cabin.

The controller thought it was a prank and dismissed the emergency call, according to recordings obtained by KUSA-TV.

The United Express plane from Peoria, Ill., was evacuated Tuesday after landing at Denver International Airport. An FAA report said firefighters extinguished a fire in the instrument panel. The cause of the fire was under investigation.

Controllers apparently realized the mistake when the pilot made another emergency call saying the plane had already landed and was evacuating on the runway. It was only then that fire trucks responded.