(AP) — Two men who were riding in a gyrocopter are alive after the copter plunged about 20 feet to the ground south of St. Louis.

The accident happened Sunday afternoon at the Festus Airport in Jefferson County, Mo. Names and conditions of the men have not been released.

Authorities say the gyrocopter crashed in a grassy area near the runway. Emergency workers arrived to find one of the men still in the aircraft. He was taken to a hospital.

The Federal Aviation Administration is investigating.

The copter is an experimental aircraft that looks like a small helicopter.