A 16-month-old boy was fatally shot by his 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.

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.

SEE MORE: Police: 3-year-old shot, killed 4-year-old sister

An autopsy was scheduled for Wednesday to determine the childs cause and manner of death.

No arrests have been made, but the case remains under investigation, police said.

When the investigation is completed, officials said the case will be sent to the Tippecanoe County Prosecutors Office for review to determine if charges should be filed.

SEE MORE: Prosecutor: 6-year-old won’t be charged after shooting teacher

According to the Giffords Law Center, Indiana has no law that requires a gun owner to secure an unattended firearm.

The nonprofit, which works to prevent gun violence, also notes that the state does not require gun owners to lock their weapons. 

Firearms are now the leading cause of death for children, according to the Centers for Disease Control and Prevention. 

Everytown for Gun Safety reports there have been more than 60 unintentional shootings by children in 2023, which have resulted in at least 25 deaths.