READING, Pa. — A hazardous materials incident involving pool chemicals sickened more than a dozen people and prompted the quick evacuation of the YMCA's central branch in downtown Reading.

A mixture of chemicals in the area of the Y's indoor swimming pool at Reed and Washington streets created a gas that caused various reactions among people inside the building Friday afternoon, including mucus, irritation, and rash, according to a city spokesman.

"What we found when we got here, from the hazmat side, was a chemical reaction going on in the sub-room below the pool, where they mix the pool chemicals to keep the pool water safe for folks to swim in," said Dep. Chief Tom Kemery, Reading Fire Department.

Between 10 and 20 people, including some children, were said to be affected. They were triaged at the city's nearby ambulance station on Walnut Street for evaluation by EMS crews. Some were transported to the hospital for further treatment, officials said.

Some 60 others were evacuated from the Y's daycare center and sheltered across the street, at St. Joseph Medical Center's Community Campus.

Firefighters used fans to clear the building of the chlorine gas before allowing people back inside shortly before 5 p.m.

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