The hotel staff and guests were evacuated.
In the US city of Marysville in 16 people were found unconscious in a hotel in Ohio, including a two-year-old child.
The victims were in the area near the pool, and the little girl — unconscious in the water, law enforcers say.
All guests and hotel staff were evacuated.
It is noted that people complained of a burning sensation in the throat and dizziness. Nine people were hospitalized, three of them are in critical condition.
The police are investigating the causes of the incident.