Carbondale, PA – High carbon monoxide levels at the Greater Carbondale YMCA sent nine people to the hospital on Christmas Eve.

A chimney blockage prevented gas from escaping the building, allowing levels to build up, said Fire Chief Thomas Brennan.

“It doesn’t have to be completely blocked, but it could have a restriction in there,” he said.

Dan Totsky, president of the YMCA board of directors, said Thursday that no one was seriously hurt, and patients were receiving oxygen treatments.

YMCA Director Steve Durkin called 911 at about 10:30 a.m. to report several people feeling ill, said Carbondale firefighter Ray Arthur.

One person had passed out, and several others were complaining of headaches by the time emergency crews reached the building, he said.

He said carbon monoxide levels as high as 800 parts per million were detected in the basement.

Officials transported the nine patients to Marian Community Hospital in Carbondale and Community Medical Center and Mercy Hospital in Scranton. Hospitals did not release information on the patients’ conditions.

Bob Flanagan, Lackawanna County emergency management coordinator, said a level of 35 parts per million would set off a household detector.

“Once you get up in the 800 ppm level, you’ve got a serious situation,” he said.

Officials said they did not know if the building is equipped with carbon monoxide detectors.

The building was shut down on Thursday to vent the gas. Crews remained to take readings.

It is unknown when the building will reopen.

Attempts to reach Mr. Durkin, who accompanied patients to the hospital in Carbondale, were unsuccessful Thursday.