An investigation continued Wednesday to determine the cause of a small plane crash that killed two pilots in southern Leavenworth County.

Investigators from the Federal Aviation Administration and the National Transportation Safety Board were working at the crash site, Leavenworth County Sheriff Dave Zoellner said. Sheriff’s officers are keeping the scene secure until investigators are through, Zoellner said.

The plane, a twin-engine Aero Commander model 500 S, crashed Tuesday morning in a field 5.5 miles south of Tonganoxie just east of Leavenworth County Road 1. It was registered to Central Airlines at the Charles B. Wheeler Downtown Airport in Kansas City, Mo. Killed were employees James Phillip Jambor, 24, of Fort Worth, Texas, and Murray Brown, 47, of Kansas City, Kan.

Central Air officials issued a statement saying that employees at the company were devastated by the deaths and that the firm is cooperating with the FAA and NTSB in the investigation.