The decision mainly concerns small arms ammunition and certain types of semi-automatic weapons of the type used in several mass shootings. In addition to the sales stoppage, they also urge their customers not to carry weapons visibly even though it is legal in several states.

"We know that the decision will trouble some of our customers, and we hope they will understand," says the company's CEO Doug McMillion, reports the BBC.

Shooting at Walmart

The decision comes after two fatal incidents during the summer in Walmart stores. On July 31, two employees were killed by a former colleague in a Mississippi store, and on August 3, an armed man killed 22 people in El Paso, Texas.

The retail giant is one of America's largest arms dealers and has over a thousand stores around the country.

The decision is criticized by the NRA

The powerful gun lobby, the National Rifle Association (NRA), criticizes the decision on Twitter and writes that Americans will seek out companies that "better understand the concept of freedom."

Walmart's market share of ammunition is about 20 percent, but that may change with the decision, McMillion says.

110 mass shootings since 1982

Weapons and ammunition represent only a fraction of Walmart's total sales, according to Burt Flickinger, chief executive of the retail company Strategic Resource Group (SRG).

He predicts that the decision will pay off in the long run and that you can now give more room to faster growing categories such as children and health.

Since 1982, there have been 110 mass shootings in the United States, according to the magazine Mother Jones.