The concrete saw was being used in a nearby suite that was under construction, and smoke detectors near the saw were covered up, authorities said.

While a cause has been determined behind what caused a carbon monoxide leak at a New England day care on Wednesday, it continues to be under investigation.

The Maine Fire Marshal's Office said carbon monoxide that prompted the evacuation of a Kittery day care and led to nearly a dozen people being treated at an area hospital came from a gas-powered saw that was being used elsewhere in the building.