Ames, IA- KCCI – Two people were overcome by carbon monoxide gas Wednesday at an Ames home.

At 11:51 a.m., firefighters were called to 1932 Bel Air Drive.

Grace Weigel, who lives at the home, and Jane Milleman, a visitor, were transported to Mary Greeley Medical Center, a news release said.

The women were then sent to a Des Moines hospital for special treatment. Their conditions are not believed to be life-threatening.

After entering the home, firefighters used a meter to measure the amount of carbon monoxide gas in the dwelling, and it showed a dangerously high reading, the release said.

The source of gas was traced to the improper use of a box fan near the home’s boiler, which forced boiler exhaust into the house instead of venting outside.

The house did not have a carbon monoxide detector.