"I feel confident in saying that it did (help) in Southaven", said Walmart spokesman Randy Hargrove in a phone interview, adding that employees guided other associates and customers to the right exits and out of danger.
Walmart banned the sale of assault-style semi-automatic rifles in 2015.
"We take seriously our obligation to be a responsible seller of firearms and go beyond Federal law by requiring customers to pass a background check before purchasing any firearm", Walmart said in the 2018 statement.
Walmart sells a range of firearms and ammunition in its stores.
McMillon must now must walk a fine line of listening to the concerns of employees like Marshall who support more gun control measures, while maintaining the company's stance on sales.
Walmart, which has been selling guns for decades, has gradually tightened its gun policies in recent years.
Walmart announced in a February 2018 statement that it had reviewed its firearm policy and chose to raise the age restriction for purchasing firearms and ammunition to 21 years old.
The Walmart logo is seen on a store in Washington, DC, on March 1, 2019. "We should all call on Walmart to do that", Volsky said. And Walmart has also instituted several other procedures to make gun sales safer. "We're focused on supporting our associates, customers and the entire El Paso community".
The weekend shooting in Texas unfolded at a popular Walmart store in the border city of El Paso, killing 22 people. "We are instead focusing on hunting and sportsman firearms".
The former Walmart U.S. CEO said the company stopped marketing handguns many years ago and now mostly sell more simple rifles and shotguns popular among outdoorsmen.
Representatives for the National Rifle Association, Everytown for Gun Safety and Brady, a gun violence prevention advocacy group, did not immediately respond to ABC News' request for comment.