CASCO TOWNSHIP, Mich. - Carbon monoxide (CO) poisoning is believed to have killed a 78-year-old woman at an Allegan County cottage and also sent her 80-year-old husband to a hospital, according to the Kalamazoo Gazette.

The visiting couple was sleeping in a bedroom at the cottage.

A faulty central heater and fan are apparently to blame, officials said, but the cause is under investigation.