Three adults and two children in a Santa Maria house were taken to local hospitals for treatment of carbon-monoxide poisoning early Sunday morning.

Santa Maria firefighters responded about 3:50 a.m. to a gas leak inside a single-family residence in the 500 block of East Alvin Avenue, according to Battalion Chief Alan Widling.

Crews arrived to find an adult man staggering out of the front door; firefighters then evacuated two other adults and two children from inside the home.

All five of the occupants were conscious and alert, but felt ill, were weak and complained of severe headaches, Widling said.

Two adults who appeared to have the worst symptoms were transported to Marian Regional Medical Center. The other adult and two children were taken to Lompoc Valley Medical Center.

Firefighters used fans to ventilate the structure. Southern California Gas Co. crews were called to the scene to help find the source of the carbon monoxide.

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Investigators suspect the leak came from the home’s forced air heating unit, which was running at the time.

Firefighters say the residence did not have a working carbon monoxide detector.

The Santa Maria Fire Department urges people to ensure their appliances are functioning properly and that residences have working carbon monoxide detectors along with working smoke detectors.