WTOC obtained surveillance video Wednesday night from the Octane Food Mart on Highway 80 in Effingham.
Monday evening, a man went behind the counter, threatened the clerk with a knife and grabbed the money.
Just as he was getting out of the store, another customer came in, realized what was going on and went into action.
The customer grabbed the robber by the shirt and yanked him back.
A sheriff's deputy spotted it, chased the robber and had to tase him to get him in custody.
They arrested 42-year-old Kevin Shuman, of Guyton, on several charges, from the robbery to assaulting an officer and more. He's in jail in Effingham County.