An armed man who was attempting to rob a neighborhood store in Chicago was fatally shot by a bystander who had a concealed carry license, police said Sunday.

A masked man, identified as Reginald Gildersleeve, 55, walked into the store around 7 p.m. Saturday on the city's southwest side, reported the Associated Press. Once inside, he brandished a handgun and announced his intent to rob the store. He then pointed the weapon at another employee and forced her to the back of the store.

The customer, who remains unnamed, took out his own weapon in response to the events that were unfolding before him and shot Gildersleeve several times. Police arrived on the scene moments later and pronounced Gildersleeve dead at 7:10 p.m., reported the Chicago Sun Times. Gildersleeve reportedly had an extensive history, including previous arrests for robbery.

It wasn't immediately clear whether the customer, who has not been identified, will face charges. Police spokesman Anthony Guglielmi said the case is under review by local prosecutors, but preliminary details indicate the customer was not at fault.

"We're looking at it as a self-defense issue at this point," Guglielmi said, according to Fox News.

Instances of bystanders firing upon lawbreakers or potential lawbreakers by concealed carry licenses holders have been on the rise in recent months. In October, a Michigan woman shot at shoplifters fleeing a Detroit-area Home Depot store, flattening a tire of their SUV. No one was hurt, and the suspected shoplifters were arrested several days later. Two other shootings in which citizens fired at lawbreakers or potential lawbreakers also happened in September in Michigan. 

Unlike this case however, the woman faces up to 90 days in jail after pleading no contest to a charge of reckless discharge of a firearm.

"It's a slippery slope" when it comes to the question of whether citizens who are licensed to carry guns should intervene in dangerous situations, if at all, Guglielmi said.

"You have situations like this," he said, referring to the fact that no one else was hurt during the foiled robbery. "And you have situations that end tragically. The department is not going to advocate for what people should or shouldn't do."