The shooting happened June 6 in Nashville, Tennessee.
Anthony Sanders, a 27-year-old convicted felon, was to go before a judge Thursday to be charged with gun possession, which is illegal for people with a criminal record like his. He had done prison time for kidnapping.
The new charge could bring a 10-year jail term if he is convicted.
Sanders was arrested Wednesday. He had spent the night in the Nashville apartment and departed the next morning, leaving the gun behind.
At least five children were there at the time.
Such tragic accidents are not rare in the United States, a country with more than 300 million guns.
In 2014, a two-year-old child killed her mother in a supermarket in Idaho by grabbing the gun in her purse.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)