Officials say a family at the Island Lakes Apartments woke up early Sunday morning to the sound of their alarm going off.
Firefighters went to the home and found elevated levels of carbon monoxide.
They say the family used the fireplace last night and closed the damper before going to bed.
But that allowed the ashes to generate enough heat to produce the potentially deadly gas.
Carbon monoxide alarms are already required in most homes, and they'll be mandatory in multi-family residences starting Jan. 1.