"If a State Fire Marshall cannot tell the difference between these detectors, how can I be expected to?" the daycare owner told families.

Building Blocks Learning Center plans to close permanently after at least 11 people were hospitalized in the gas leak.

Carbon monoxide is a colorless, odorless, tasteless gas that can accumulate in homes and kill without warning.

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.

11 people are at a New Hampshire hospital after a possible carbon monoxide incident at a day care in Maine. Around 3:30 p.m. on Wednesday, dispatch in Kittery, Maine, got a call about a possible carbon monoxide incident at a day care on Route 236 in town, the fire department said.

A Kittery child care center where nearly a dozen people were treated for carbon monoxide poisoning last week did not have a working carbon monoxide detector.

A report from the state fire marshal's office sent to parents shows Building Blocks Learning Center had several violations, including a lack of carbon monoxide detectors and fire extinguishers.