COTTAGE GROVE, Wis. -- A construction crew was treated for carbon monoxide poisoning in Cottage Grove Tuesday.

Fire crews were called to a construction site where workers were suffering from symptoms of inhaling too much carbon monoxide.

They were operating a piece of equipment in the basement that apparently was not properly ventilated.

"After four to five hours of operating the machinery you're gonna have some pretty significant levels," said Cottage Grove Fire Dept. Capt. Mike Boisen. "We had levels approaching 200 parts per million down there."

Humans can start experiencing carbon monoxide poisoning symptoms at 40 to 60 parts per million.

Three of the five-crew members were taken to area hospitals with non-life threatening injuries.