A working CO alarm alerted occupants of a Russell Street home to elevated carbon monoxide levels Saturday night.
Sarnia Fire and Rescue responded at around 8 p.m.
Public Education Officer Mike Otis said the residents and their pets were able to get out of the home safely.
He said a gas stove was to blame.
"A lot of people don't realize that. They think it's just their furnace as giving off carbon monoxide but a lot of homes have six or seven different sources of carbon monoxide," said Otis. "Furnaces, hot water heaters, any fuel-burning appliance, fireplace and attached garage are all sources of carbon monoxide."
All homes and apartments in Ontario are required by law to have a CO detector adjacent to all sleeping areas or face a fine of $360 or more.
Carbon monoxide is the leading cause of accidental poisoning deaths in North America and 500 people a year die from it.