Rochester, Minn.- Carbon monoxide poisoning caused the death of a 3-year-old girl at her family’s home near Rochester, authorities said.

An autopsy confirmed that Hannah Griggs died from breathing in the toxic gas, Olmsted County Sheriff’s Capt. Joe Loftus said.

Authorities were trying to determine the source and cause of the carbon monoxide, Loftus said.

Hannah was the daughter of Melissa and Jason Griggs. Jason Griggs called 911 around 1 a.m. Friday to report his wife had fallen.

Emergency crews were unable to revive Hannah. The parents and their younger daughter, 11-month-old Calli, were seen and dismissed from Saint Marys Hospital in Rochester.

The family has lived in the home in Oronoco Township just north of Rochester for five months, said Chelsey White, a relative who spoke on behalf of the family.

The Griggs’ home had smoke detectors but no carbon monoxide detectors, White said.