The Ontario Fire Marshall is investigating after a mattress fire in Tecumseh sent a husband and wife to hospital.
Tecumseh fire officials say the cause of the fire is thought to be careless smoking.
The fire was contained to a bedroom and extinguished within 15 minutes of fire personnel arriving.
There were no working smoke alarms in the home.
Tecumseh Fire Chief Doug Pitre said the two elderly residents are being kept in intensive care for precautionary purposes.
"Because of the amount of carbon monoxide in their blood and their age, they will monitor them," said Pitre.
Charges, if any, from not having working smoke alarms will be determined by the OFM.
Investigation results are expected later today.
Link to original article in CBC News: Tecumseh home had no working smoke alarms, fire sends two to hospital