INDIANAPOLIS -- The father of a 4-year-old girl who police say was fatally shot by her 5-year-old brother Sunday believed the gun was unloaded, police said.

Police said the county prosecutor's office will decide whether to file charges against the father, James Booher, in connection with Makayla Booher's death.

Authorities said the boy took a handgun from the top of a bookcase and shot Makayla at their home in the 6100 block of Massachusetts Avenue at about 10 a.m. Sunday.

James Booher told investigators he thought the .40-caliber semiautomatic gun had been stored unloaded because its magazine had been removed. Police said that despite the magazine's removal, a bullet still was chambered in the gun.

"This has happened in police officers' homes where police officers have thought they emptied their weapons and ended up shooting themselves in the arm of the leg or even the head," Indianapolis police Sgt. Matt Mount said.

Police said the boy used a chair to reach the top of the bookcase. They said James Booher, the children's 15-year-old stepsister and another relative were at the home when the shooting happened.

"The siblings ... are going to be impacted for the rest of their lives, especially the 5-year-old," Mount said. "When he reaches that cognitive ability to understand really what is going on here, it's something that he'll have to be living with."