As reported, a Bradenton, Florida man used his handgun to stop three armed robbers:

Police say that three armed robbers who were dressed in black and wearing masks approached a would-be robbery victim.  One of the robbers is said to have pointed a gun at the armed citizen, according to news reports.  Acting in self defense, the armed citizen drew his own gun and fired, fatally wounding that robber and sending the other two robbers fleeing, according to police.  No injuries to the armed citizen or any bystanders were reported.

I would note that this self defense shooting, like the overwhelming majority of self defense shootings, did not result in any innocent bystanders being harmed.  Anti gun people like to suggest that self defense gun uses result in wild west shootouts, leaving innocent people injured or killed.  That is just not reality, plain and simple.  The fact is that such cases of bystander injury are quite rare, and armed citizens have been shown to be 5.5 times less likely to shoot the wrong person than the police.