Authorities investigating the deaths of a man and two children whose bodies were found in an Indiana home said firefighters detected high carbon monoxide levels inside the residence.

The bodies of the 24-year-old man, a 3-year-old boy and a 21-month-old girl were found Sunday afternoon in the home in the city of Muncie.

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Delaware County Coroner Gavin Greene announced on Monday the firefighters' findings, The Star Press reported. Carbon monoxide is a toxic, odorless gas.

Autopsies were conducted Monday on the three victims, but Greene said the death investigation is ongoing, pending toxicology results and a pathologist's findings.

Deputy Police Chief Melissa Criswell said city police and fire personnel were also investigating the deaths in Muncie, which is located about 60 miles northeast of Indianapolis.