KOCO-TV, Oklahoma City, said the crash occurred Wednesday in an open field. Oklahoma Highway Patrol said there were no fatalities, but the injuries are serious and may include broken bones.
Authorities said the helicopter was headed to the Creek National Community Hospital in Okemah, Okla., to assist with the transportation of a patient.
KOCO-TV said the helicopter took off from Seminole Airport and was not carrying any patients. At least two ambulances and the OHP were on the scene.
Authorities said they are still investigating the cause of the crash, but indicated engine failure might be to blame.