A level 1 mass casualty event was declared in Pennsylvania on Tuesday morning after 32 people, mostly children, were hospitalized following a massive carbon monoxide leak at an Allentown daycare. Firefighters initially arrived on the scene to respond to a report of an unconscious child, but the carbon monoxide monitors on their gear alerted them to the larger problem. Multiple other people were already exhibiting symptoms of carbon monoxide poisoning, authorities said. The evacuation of Happy Smiles Learning Center sent 28 children and 4 adults to area hospitals, and utilized every ambulance in the city, reported WFMZ-TV. The leak at the facility, which did not have a carbon monoxide alarm, comes just a month after Pennsylvania legislators passed a law requiring daycares have the devices in their buildings, though the 30-day deadline to comply has not yet passed. All the victims were reported in stable condition.