Authorities say two people needed treatment at the hospital after dangerously high levels of carbon monoxide were found in their Kennebunk home. The homeowners called 911 at about 10 a.m. on Sunday to report that their carbon monoxide detector was going off in the Old Port Road home. Firefighters responded and tested the air in the home, finding high levels of the deadly gas. Both residents were taken to Southern Maine Medical Center in Biddeford for evaluation. Firefighters say says the basement furnace is the likely cause. Authorities say carbon monoxide is colorless and odorless, so a detector is essential. Exposure to the gas can cause headaches, nausea and blurred vision.