A 3-year-old boy in Columbus, Ohio, fatally shot himself after finding an unsecured gun inside his home on Monday, police said. 

The Columbus Division of Police said 3-year-old Cartier Smith died Monday morning after unintentionally shooting himself inside an apartment complex on the city's Southeast Side, and his mother has been charged, according to CBS affiliate WBNS. 

Police reportedly were called to the apartment just before 9 a.m. for reports of a juvenile who had shot themselves. The boy was taken to a local hospital in critical condition but later died, the TV station reported. 

Authorities reportedly said their initial investigation determined that the victim's mother, 29-year-old Carley Dials, and a man were sleeping in the upstairs bedroom. WBNS reported, citing police, that Dials found a handgun on the bedroom floor before going to bed. The gun was brought to the apartment by the man, the news outlet reported.

Police said the gun was placed between the mattress and the wall of the bedroom by Dials around 3 a.m., WBNS reported. The boy walked into the bedroom in the morning and somehow found the gun and fatally shot himself, authorities reportedly said. 

Dials was charged with involuntary manslaughter. The man, who was not identified, was charged because police said he was not allowed to have a gun due to a previous felony conviction. He was arrested after fleeing the scene before police arrived. He also had an active warrant for a probation violation, the news outlet reported. 

According to a report from the Centers for Disease Control and Prevention, unintentional firearm injury is the leading cause of death among children in the United States ages 0-17. The report added that most unintentional firearm injuries among children occur within the home.