The Natrona County Sheriff's Office is investigating the death of a nine-month-old girl that occurred last week at a residence in the 2700 block of Robertson Road, a sheriff's spokesman said.

"Deputies responded (Thursday) February 5, 2015, to a residence in Natrona County approximately 9:45 p.m. for an unconscious infant," Aaron Shatto said Friday.

The child was taken by Life Flight to Denver Children's Hospital and died Sunday.

Some one from inside the residence, but it was not a parent, called law enforcement. There were two other children in the residents. Shatto did not say whether those children have been removed from the residence.

"Since we received the call, the child has passed away, and we are investigating the death at this time," Shatto said.

"Any time a child of that age dies, there's a lot of unknowns, and we're investigating the cause of death, and what may have caused her death.," he said.

The cause of death has not been determined. The Sheriff's Office is waiting for results from doctors and autopsy reports. The autopsy is being done in Adams County, Colo.

Authorities have executed multiple search warrants on the residence for clothing, bedding and other materials.

This story will be updated.