Detective Randy Stevens says the child apparently unlocked a door at his nearby home, got out, then crossed a street to reach the discount store.
Store surveillance video shows the unidentified boy trying one of the front doors to a Family Dollar store about 3 a.m. Monday, only to find it locked. But the second door was unlocked and the child went inside.
That triggered the silent alarm.
"When the officers got there, he was showing them his toys," said Officer Crystal Holmes.
Child Protective Services says the boy will be allowed to stay with extended relatives while they review the incident.