1 dead, 4 sickened by CO poisoning at ice fishing house

One woman was killed and four others were sickened by carbon monoxide poisoning at an ice fishing house on a lake near the Iowa-Minnesota border Sunday afternoon.

The 21-year-old woman was found unresponsive in an ice fishing house on Lake Wilmert in Martin County, Minnesota shortly before 2 p.m., according to the Martin County sheriff's office. She was pronounced dead at the scene.

One man was flown the Mayo Clinic Hospital in Rochester and three other adults went in to nearby hospitals to be treated for carbon monoxide poisoning. 

The identity of the woman who was killed has not been released. The cause of death remains under investigation.