Federal Aviation Administration spokesman Lynn Lunsford says the Eagle Med helicopter had left Oklahoma City's Integris Baptist Medical Center to pick up a patient about 90 miles away at a hospital in Okeene on Thursday night.
It crashed about 8 p.m. near Kingfisher, which is about 50 miles northwest of Oklahoma City.
Lunsford says three people were on board the helicopter and one of them survived. He says another medical helicopter was dispatched to the scene to transport the survivor back to Oklahoma City.
Lunsford says investigators with the FAA and the National Transportation Safety Board are on their way to the crash site.