Hebron, KY – Cincinnati.Com – Some hotel guests had to be treated on Monday afternoon for high levels of carbon monoxide that came from a pool heater, officials said.

The Hebron Fire Department said it was called to the Courtyard hotel shortly after noon for some swimmers who had passed out. By the time rescue crews arrived, they’d regained consciousness, so the swimmers were examined and then released.

Investigators found that the chlorine levels in the water were normal, but carbon monoxide levels in the pool area were high — between three and nine times acceptable levels.

Some of the swimmers had returned to their Courtyard hotel in Covington, so fire officials tracked them down and found that they, too, tested high for carbon monoxide.

They were taken to local hospitals for treatment. So far, their conditions have not been released.

The hotel turned off the heater and ventilated the area, and officials said they advised hotel management to have the heater fixed.