A nurse, paramedic and pilot were killed when a medical helicopter crashed Wednesday night in Iowa about 30 miles south of the Minnesota border.

The chopper, based at Mercy Medical Center-North Iowa Hospital in Mason City, Iowa, was on its way to pick up a patient in Emmetsburg, Iowa, when it plunged into the ground just north of Ventura in Cerro Gordo County at about 9 p.m., the Mason City Globe Gazette reported. Witnesses reported a fireball.

ATVs and snowmobiles were being used by emergency responders to get to the crash site, the Globe Gazette reported.

A hospital spokeswoman said the staff was devastated, the newspaper reported. The cause of the accident was not immediately known, and the Federal Aviation Administration will investigate, the newspaper said.