CROFTON, Nebraska — Two small planes crashed into fields in northeastern Nebraska on Monday, killing at least one person.

The two crashes occurred less than half an hour apart around 9:30 a.m. A Rans S-19 plane crashed first near Crofton in Knox County. Then a Piper PA-28-140 plane crashed shortly after near Wayne in Wayne County.

The Nebraska State Patrol and the Knox County Sheriff’s Office said the pilot died in the crash. There was no one else on board the plane. The pilot’s name was not released Monday afternoon.

The Wayne County Sheriff’s Office has not yet released details about the accident, which is under investigation there.

The National Transportation Safety Board is sending investigators to the state to determine why both planes crashed. But the agency’s final reports normally take more than a year to complete.