LANCASTER, S.C. -- Authorities say a loaded gun was left in the room where a 2-year-old child suffered a fatal gunshot wound to the chest in South Carolina.

The Rock Hill Herald reports that arrests warrants show Jacarion Gladden's 26-year-old mother, Toni Lashay Gladden, knew her live-in boyfriend, 18-year-old Shazeem Tyrell Hayes, kept the handgun unsecured in the living room. Warrants say the couple entered the living room after hearing a gunshot and found the child shot. They crashed the car on the way to the hospital, where he later died.

Lancaster Police Chief Scott Grant described the boy's death to CBS affiliate WLTX as "extreme negligence on behalf of those who should have been his most ardent protectors."

"Last night was probably the darkest night in the history of the Lancaster police department, at least in the 20 something years I've been here," Grant told reporters.

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Grant said investigators found out what happened to the boy only after a "full night of lies and avoidance."

The gunshot is not believed to have been intentional.

Hayes is charged with felony unlawful conduct toward a child. He is on probation for a 2016 conviction for weapons and burglary. Gladden is charged with misprision of a felony and unlawful conduct toward a child.

It's unclear if they have lawyers.