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

The shooting killed Isiah Johnson, Tippecanoe County Coroner Carrie Costello said.

"Detectives with the Lafayette Police Department determined that the child was shot by his five-year-old sibling, who was able to gain access to a weapon in the apartment," police said in a news release Tuesday.