A shooting inside an Atlanta grocery store resulted in the death of a cashier. The worker was shot dead Tuesday after arguing with a customer over his face mask.

The Georgia Bureau of Investigation said the customer had argued with the cashier, left the store without buying anything, and then returned to gun down the cashier. The cashier was pronounced dead on arrival at the Grady Memorial Hospital.

The shooter also fired at the store’s security guard and responding officers, including a reserve deputy with the DeKalb County Sheriff’s Office. Another cashier was reportedly also shot but survived with minor injuries.

DeKalb County Sheriff Melody Maddox the officer that was shot was in stable condition and had survived the incident thanks to his bulletproof vest.

The shooter was arrested by responding officers after he was shot. The suspect is reportedly also in stable condition after he was treated at another hospital in Atlanta.

Maddox said they are still investigating the incident, adding that the state’s mask policy still depended on retailers. He said face masks are still a sensitive subject for a lot of residents and he urged everyone to stay safe.

The Centers for Disease Control and Prevention recently relaxed its mask guidelines, making it difficult for some retailers to make masks mandatory. Retail workers have often been forced to become “mask police” to enforce a store’s rules, which may be different to other establishments.

“Essential workers are still forced to play mask police for shoppers who are unvaccinated and refuse to follow local COVID safety measures. Are they now supposed to become the vaccination police?,” the United Food and Commercial Workers International union – a critic of the FDA’s recent mask policy – said in a statement.