South Bend police released footage of the home invasion, which happened around 10:30 a.m. on Sept. 30.
Four men, at least three of whom were armed with handguns, barged into the house after another child answered the door, police said.
The video shows the men pointing their guns at an adult woman in the home before the 5-year-old boy jumped into action hitting one of the armed suspects.
Police said the suspects fired shots and fled the scene, but no one was injured.
"This video is extremely disturbing," police said. "You can see a little boy hitting one of the armed suspects as he tries to defend his home. It is our job now to defend him."
Anyone with information is urged to call Crime Stoppers at 574-288-STOP or 800-342-STOP.