Local Fire Chief Jay Riley told the newspaper that the source of the carbon monoxide was unclear but everyone who was hospitalized had been in the hotel’s pool area.

Riley said the victims included both children and adults. He did not provide exact ages.

Authorities said they received a 911 call Saturday evening about a 2-year-old girl who had either fallen into the pool or was found in the pool unconscious at the Hampton Inn in Marysville. More 911 calls soon followed about unconscious people or others who reported symptoms such as dizziness and a burning in the throat, Marysville Police Chief Tony Brooks said.

The hotel was evacuated shortly after. Brooks told the newspaper that all of the injured were alive when they were transported and that seven of the patients were in critical condition.

Two others were treated at the scene, and five more later sought treatment on their own at a hospital, Brooks said.

The Dispatch could not reach any members of the hotel management late Saturday. Riley said a Hampton Inn maintenance team was en route from out of state.

Marysville is about 30 miles (48 kilometers) northwest of Columbus.

How Dangerous is CO Poisoning in Ohio?

Despite its many sources, CO isn’t normally a danger, as adequate ventilation keeps it from reaching anywhere near poisonous levels under normal circumstances. CO only becomes a hazard when a room or building lacks proper ventilation or when appliances that produce it are improperly maintained or installed. Improperly maintained or installed furnaces, chimneys, water heaters, etc. can all put out dangerous levels of CO. “Efficiencies” and other types of very small apartments and homes are especially at risk of CO build-up due to their size.

How Does Carbon Monoxide Cause Damage in the Body?

Recent studies suggest carbon monoxide causes damage in other ways than by depriving the body of oxygen. Scientists haven proven that CO has neurotoxic effects because it creates a series of biochemical events. These events create a significant increase in oxidative injury to the structures surrounding blood and lymphatic vessels, nerve cells, and neurons.

Carbon monoxide is a colorless, odorless, and tasteless gas that can be fatal if inhaled. It is the leading cause of poisoning deaths in the United States.

Carbon monoxide is produced by the incomplete burning of fossil fuels such as natural gas, gasoline, kerosene, oil, propane or coal. It can also be produced by burning charcoal indoors or running a car in an attached garage.

The most common symptoms of carbon monoxide poisoning are headache and nausea. Other symptoms include dizziness, weakness, confusion and chest pain. If left untreated these symptoms may lead to death by suffocation from lack of oxygen in the blood stream or heart attack due to reduced blood flow to the heart muscle.