It appears carbon monoxide killed a 77 year old farmer, his dog and 25 head of cattle.

It happened Monday afternoon in the town of Wilson, near the county line in Northern Dunn County.

The Sheriff's Department got the emergency call around 1:30 about a man who collapsed in the barn.

He and the animals were already dead when rescue crews arrived.
The preliminary cause of death is carbon monoxide poisoning from a tractor left running in the barn.

Investigators are not releasing the victim's name.