The charred wreckage of Mercy Medical Center-North Iowa's Air-Med helicopter lays along the edge of an old fence line two miles northwest of Ventura, Iowa Thursday morning, Jan. 3, 2013. Authorities have identified two of three people who were killed when the medical helicopter crashed Wednesday night, Jan. 2, 2013; nurse Shelly Lair-Langenbau and paramedic Russell Piehl., both of Mercy Medical Center-North Iowa. The pilot was not identified. Witnesses told deputies that the helicopter burst into flames when it went down just north of Ventura in Cerro Gordo County. (AP photo,Jeff Heinz,Globe Gazette).

A preliminary federal report suggests that icy conditions will be among the factors checked by investigators trying to determine what caused the fatal crash of a medical helicopter in northern Iowa.

Mason City television station KIMT says the report released Wednesday didn’t include any conclusion about the crash cause. The pilot and two others on board died the night of Jan. 2.

The helicopter had been headed to Emmetsburg, about 80 miles west of Mason City, to pick up a patient when it slammed into the ground just north of Ventura about 9 p.m. The report says several witnesses mentioned icy conditions at the time.

The three victims were identified as nurse Shelly Lair-Langenbau, paramedic Russell Piehl and pilot Gene Grell.