POTOSI, Mo. — Authorities say a pilot was hospitalized after an ultralight aircraft he was flying crashed in a field in eastern Missouri’s Washington County.

The Missouri State Highway Patrol said the pilot sustained serious injuries during the crash about 8:30 a.m. Monday not far from the end of the Washington County Airport runway near Potosi.

It was not immediately clear what caused to aircraft to go down.

The Federal Aviation Administration is investigating.

The pilot’s name was not immediately released.