ST. CHARLES, Mo. (AP) — The two people killed when their plane crashed in eastern Missouri on Saturday were experienced pilots from Ohio who were flying to Denver to pick up cargo, authorities said Tuesday.

George King, 55, of Westerville, Ohio, and Amanda Youngblood, 35, of Huber Heights, Ohio, were killed in the crash Saturday about 6 miles northwest of Defiance in St. Charles County, air safety investigator Mike Folkerts with the National Transportation Safety Board, said at a news conference.

No one else was on board the plane.

The pilots worked for cargo airline AirNet II LLC, based in the Columbus, Ohio area, the St. Louis Post-Dispatch reported.

Their 1981 twin-engine Beechcraft Baron 58 crashed about 9 minutes after taking off from Spirit of St. Louis Airport in Chesterfield, the NTSB said.

Investigators are trying to determine what caused the plane to go into a rapid descent after reaching an altitude of 8,000 feet, Folkerts said.

The pilots did not transmit a distress call before the crash but Folkerts said investigators are reviewing some communications that indicated a problem with the flight.