Excerpts from evanstonnow.com:

Eight people were taken to local hospitals Monday morning (11/14/16) after Evanston firefighters responded to a report of a carbon monoxide alarm going off in a two-family home at 1404 Pitner Ave.

Fire Division Chief Paul Polep says when firefighters arrived they found carbon monoxide readings of 200 parts per million, adding that typically a home CO detector would go off at a level of about 35 ppm.

Some of of the residents of the building complained of headaches, a common symptom of carbon monoxide poisoning, and were taken to the hospitals for evaluation.

Those taken to St. Francis and Evanston hospitals included three adults and five children. All are now said to be in stable condition.

… the caused the carbon monoxide buildup … hasn’t been determined