A 16-month-old boy was fatally shot by a 5-year-old sibling at a northwestern Indiana apartment, authorities said.

The older sibling accessed a handgun inside the Lafayette apartment on Tuesday afternoon and fatally shot the boy, who was identified as Isiah Johnson, police said late Tuesday.

An autopsy was scheduled for Wednesday to determine the child’s cause and manner of death.

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Lafayette police Lt. Matt Gard said someone outside of the apartment called 911 after the shooting to report that a child was not breathing.

"There was one adult and two children inside the apartment," Gard told the Journal & Courier.

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No arrests had been made as of Wednesday morning and the case remains under investigation, police said.

When the investigation is completed, officials said the case will be sent to the Tippecanoe County Prosecutor’s Office for review to determine if charges might be filed.

Lafayette is located about 60 miles north of Indianapolis.