ALLENTOWN, Pa. (AP) — An apparent carbon monoxide leak at a Pennsylvania day care center sent about two dozen children to the hospital early Tuesday, but none of the injuries were considered serious, authorities said.

Emergency responders went to the Happy Smiles Learning Center in Allentown, Pennsylvania, on reports of an unconscious child. The building was evacuated after air quality detectors worn by firefighters were triggered.

The 25 children were being evaluated at the hospital, and all were listed as stable, authorities said. Eight staffers were also in the building.

The cause of the leak is under investigation.

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