reporter: tonight, investigators racing to find out what caused that horrific carbon monoxide poisoning at a hotel outside columbus, ohio. looking into heaters, hvac systems, anything that could have developed, produced carbon monoxide. reporter: multiple people found unconscious in and around the indoor pool, including a toddler. now a report of three different children unconscious. reporter: the 2-year-old s family telling abc news her head started to bob, and she lost consciousness as her mother was holding her in the water. six children and five adults hospitalized. some victims reporting symptoms like dizziness and burning in their throats. hotel guests evacuated. including families in town for a wrestling tournament at an area high school. coach nicholas holmes says three members of his team were among those affected. this is impacting us seriously, and we just want to pray for these individuals and ask that everything be all