Streamwood, IL – Two people were taken to the hospital Saturday night as a precaution after a carbon monoxide leak in a Streamwood town home complex, authorities said.

Firefighters responded about 10 p.m. to a man and woman experiencing symptoms of dizziness and nausea inside a unit on the 3000 block of Kingston Court, Lt. Steve Laker said.

An air monitor showed that the levels of carbon monoxide at 200 to 300 parts per million, Laker said. The odorless, colorless gas can cause unconsciousness at 800 parts per million in a few hours.

The residents were alerted by a carbon monoxide alarm and called 911, Laker said.

A man and a woman were taken to St. Alexius Medical Center in Hoffman Estates as a precaution, Laker said. A third person, who was not experiencing similar symptoms, refused treatment, Laker said.

Firefighters found a faulty furnace as the source of the leak in a basement in the complex, according to Laker.

Streamwood officials are expected to check the status of repairs to the furnace Sunday.