UPDATE: Four people have since been released from the hospital after 11 people were initially hospitalized after inhaling dangerous amounts of carbon monoxide at the Hampton Inn in Marysville on Saturday. Read the full update on this story.
MARYSVILLE — Eleven people were transported from the Hampton Inn in Marysville in Union County to area hospitals Saturday night — including seven considered in critical condition — in what local officials are calling carbon monoxide poisoning.
Marysville Fire Chief Jay Riley said the exact source of the carbon monoxide was unclear as of late Saturday evening, but any potential sources had been shut off and the building was cleared of people.
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All of the injured taken to hospitals had been in the pool area. Riley did not have ages of any of the victims immediately available, but said there were both children and adults.

Two others were treated at the scene, and five more later sought treatment on their own at Memorial Health Hospital in Marysville, Marysville Police Chief Tony Brooks said.
What happened at the Hampton Inn in Marysville, Ohio?
Brooks said the first call came into 911 about 5:30 p.m. that a 2-year-old girl had either fallen into the pool or was found in the pool unconscious at the hotel at 16610 Square Dr. More calls to authorities about unconscious people followed, with others reporting symptoms such as dizziness and a burning in the throat, Brooks said.
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The Marysville Fire Department and Marysville Police called for help from multiple departments, and the hotel was evacuated. All the other guests and staff left on their own, officials said, and hotel management made accommodations to have them stay at other hotels.
BREAKING: 8 people taken to hospitals from Hampton Inn in Marysville.
Initial 911 call reported 2yo girl unconscious in the pool.
People were dizzy and had a burning sensation in their throats.
No conditions or other ages yet.
Possible carbon monoxide. Still investigating a pic.twitter.com/tuj0GZy4O7
— Mike McCarthy (@mikewsyx6) January 30, 2022