An irate customer fatally shot a 26-year-old female employee and critically wounded her 24-year-old female co-worker shortly after 6:30 p.m on Sunday over "too much mayo on a sandwich," Atlanta Police Deputy Chief Charles Hampton Jr. said in a news conference. 

Atlanta police arrested a 36-year-old man in connection to the fatal shooting late Sunday following a tip from a citizen, he said. 

Hampton told reporters police did not want the focus to be on the particulars of the sandwich order that led to the shooting but instead on the issue of gun violence. 

The 5-year-old son of the critically injured employee was also in the restaurant during the shooting, Hampton said. The child was uninjured but witnessed the incident, he said, and will likely "have to go through some trauma counseling." 

Willie Glenn, the owner of the restaurant, told CBS46 that the two victims of the shooting were sisters. 

Glenn said that an armed store manager attempted to stop the suspect and ended up exchanging gunfire with him, leading to a "wild shootout in the parking lot," CBS46.com reported.