MARYSVILLE — Nine 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.

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.