Pennsylvania authorities say that more than two dozen children were sent to the hospital due to an apparent carbon monoxide leak at a day care center.

Emergency responders got a report of an unconscious child at the Happy Smiles Learning Center in Allentown, Pennsylvania. After they arrived on the scene, the firefighters’ air quality detectors were triggered, causing the building to be evacuated.

Authorities confirmed that the 25 children were under evaluation at a local hospital. None of the injuries were considered to be serious, and all of the children were listed as stable.

Eight staff members had also been present in the building.

Authorities are currently investigating the cause of the carbon monoxide leak.

Source: NPR