(CNN) — A medical helicopter crashed Monday night in northern Illinois, killing all three crew members, authorities said.
A pilot and two flight nurses were on board the chopper when it crashed near the city of Rochelle, about 75 miles west of Chicago, the Federal Aviation Administration said. The helicopter was not carrying any patients at the time.
The copter, which was registered to Rockford Health System, was flying from Rockford to a hospital in Mendota.
The cause of the crash is unknown. The FAA will deploy a team early Tuesday to investigate.