Sgt. Kevin Cummings said officers were called to the 800 block of West Valley Street around 6 p.m. Wednesday.
They were told a man in a blue pickup truck approached the child around 1:30 p.m. as he was playing in the yard with his 3-year-old sister.
The man in the truck allegedly pointed a gun at the boy's head and took a pit bull dog.
Sgt. Cummings said a babysitter was inside at the time and did not see anything, but she shared the report with the child's mother when she came home. That's when police were notified.
Police ask anyone with information to all the Tips Hotline at 816-238-TIPS.