Authorities say 4-year-old Kasii Haith was killed in the attack, and his pregnant mother, identified as 24-year-old Kyiesha Haith of Camden, Delaware, suffered injuries.
The attack happened at 4:00 p.m. Wednesday in the 900 block of Edwardsville Road near Felton.
Kyiesha Haith was inside a home visiting a friend as her 4-year-old son was playing outside, near the homeowner's three pit bull terriers.
At some point the mother Kyiesha looked out and saw the dogs attacking Kasii.
The dogs' owner called 911 and the mother ran out and tried to pull the animals off her son.
Police say two heating contractors working in the neighborhood rushed to her aid, hitting the dogs with PVC pipe and separating them from the boy and his mother.
Medics and state troopers arrived on the scene and administered first aid to Kasii, but he succumbed to his injuries and was pronounced dead at the scene.
Kyiesha was taken to Kent General Hospital where she was treated for her injuries.
The dogs have been removed from the home. Delaware Animal Care and Control spokesperson Lisa Chase says the pit bulls have tested negative for rabies.
Police say Kyiesha told them her son had been around the dogs many times before.
An investigation is underway.