Fire and EMS were dispatched to the YMCA in Fort Thomas shortly before 11 a.m.
Kathy Lehr, Interim Executive Director for the Greater Cincinnati YMCA told FTM, "The Y is very interested in the health and safety of our children and that's our utmost concern and we are investigating. We have a full compliment of individuals looking into the situation to ensure that our pool is safe for all."
Officials say that proper precautions were taken by YMCA staff.
The outside pool has been cleared and will be shut down for the day. Lehr said that she wasn't sure when the pool would be reopened, however the indoor pool will stay open.
Previously other media outlets had reported that a chlorine spill caused the children to become sick, but according to Lehr that has not been confirmed.
"We don't know that it was a chlorine spill. We don't know what it was," she said.
Parents of the children at the YMCA were immediately notified of the situation.