Omaha, NE — Nearly two dozen people, including several young children, living in a northwest Omaha home were treated for carbon monoxide poisoning after walking into a hospital, officials said.

The incident happened late Tuesday night, when 22 people — all members of the same family — walked into an Omaha emergency room displaying symptoms of carbon monoxide poisoning, officials said. Among them were at least seven children under the age of 12.

The family is from Myanmar, officials said. Officials said firefighters and utility crews were working to determine the source of the carbon monoxide, a colorless, odorless gas that can cause illness and death.