Phoenix police say an elderly couple and a firefighter are recovering after an incident involving carbon monoxide. Firefighters from Phoenix and Scottsdale responded Sunday morning to a call about a woman complaining of head pain, shaking and nausea. When firefighters arrived, they found the woman and her husband experiencing similar symptoms. The couple was transported to the hospital for treatment. One of the responding firefighters soon began feeling nauseous and lightheaded. Fire crews later discovered that a vehicle in the couple's garage was running and emitting exhaust into the garage and home. Authorities say the vehicle was last used Saturday evening and may have been running through the night. The names of the couple and firefighter weren't immediately released.