Employees at Mercy Medical Center in Mason City, Iowa, were "devastated" upon learning the news, hospital spokeswoman Jodi Ball said. Killed Wednesday night were a nurse, Shelly Lair-Langenbau; a paramedic, Russell Piehl; and an unidentified pilot with Med-Trans, the helicopter service operating the aircraft.
The trio were en route to Emmetsburg, Iowa, to pick up a patient, Ball said.
Federal Aviation Administration officials are investigating the crash. The cause has not been identified.
Witnesses told the Mason City (Iowa) Globe Gazette they heard the helicopter flying low overhead and a short time later saw a large explosion.
"Me and the wife were looking out the window and wondering what it was and then the sound quit for about a second or two and then just a big ball of fire at ground level," witness Butch Koziesk said.
The Globe Gazette said emergency responders were using ATVs and snowmobiles to access the crash site in rural Ventura, Iowa.