SPRINGFIELD, Ohio (AP)—Federal officials on Wednesday began their investigation of the crash of a commuter plane that killed a flight instructor from Illinois and two recently hired pilots.

Investigators from the National Transportation Safety Board and the Federal Aviation Administration were called after Tuesday’s crash of the Piedmont Airlines plane near Springfield Municipal Airport, south of the city.

The plane, a British Aerospace Jetstream 31, was based in Dayton, said Calvin Humphrey, president of Jetstream International, which operates a commuter line for Piedmont. The airline uses the Springfield airport for training, he said.

Mike Dacy, Jetstream International’s vice president and general manager, said the company does not know what caused the crash and expects federal investigators to take several days to make a determination.

“We’re as anxious to know as everybody else,” he said. “But until the (Federal Aviation Administration) and National Transportation Safety Board investigate it, I don’t know that anybody will know.”