Investigators said the bullet struck the child in the head, near one eye.
The boy's father was downstairs with another child when he heard a gunshot.
According to authorities, the boy was thought to have been asleep. He apparently woke up and walked into another room, where the gun was on what the sheriff described as "a tall dresser."
The Fort Bend County Sheriff's Office shared a message on Twitter confirming the boy's death writing, "It's been a difficult week. We're sad to report the 3-year-old involved in the accidental shooting Friday in Firethorne has passed. We send our thanks to all that made #PrayforRadyn a national trend."
It’s been a difficult week. We’re sad to report the 3-yr old involved in the accidental shooting Friday in Firethorne has passed. We send our thanks to all that made #PrayforRadyn a National trend. pic.twitter.com/0y8teeMObm— FBCSO Texas (@FBCSO) June 24, 2019