Walmart employees pay their respects at a makeshift memorial for the shooting victims, at the Cielo Vista Mall Walmart in El Paso, Texas, on August 6, 2019. - The August 3 shooting left 22 people dead. US President Donald Trump will visit the Texan border city August 7, and will also travel to Dayton, Ohio where a second mass shooting early August 4 left another nine dead

In the wake of the weekend's deadly shootings in El Paso, Texas, and Dayton, Ohio, a pair of Walmart employees are joining a number of gun control advocates, questioning the retail chain's sale of guns and ammunition and encouraging other employees to join in their protest.

Thomas Marshall, 23, a Walmart employee based in San Bruno, California, used email and internal Walmart Slack channels to reach out to fellow employees this week, encouraging them to call in sick Tuesday, to take part in a walkout Wednesday and to sign a Change.org petition that calls for an end to the sale of guns and ammunition in all Walmart stores.

"We are all concerned employees, and Walmart says it values the outlook of its employees," Marshall told NBC News. "We feel as if we can make a noticeable difference."

Marshall said he's troubled by Walmart's decision to continue to sell firearms, even after the mass shooting in one of its own stores in El Paso killed at least 22 Saturday.

"If I do wind up getting fired for this, that is a risk I am willing to take," Marshall said on MSNBC on Wednesday.

According to Walmart spokesperson Randy Hargrove, approximately half of the 4,700 Walmarts in the United States sell guns and many more sell ammunition. Hargrove said that there are no plans to change the retail giant's policies since the weekend shootings or as a result of Marshall's call for an employee walkout.

"There's been no change to our policy regarding firearms," Hargrove said. "Our focus has been on our associates and the entire El Paso community."

Assisting Marshall with gun sales protest efforts is another Walmart employee, Kate Kesner.

Kesner and Marshall said that their work accounts were disabled by Walmart after they attempted to organize the protests.

Hargrove confirmed that those company accounts had been suspended and would remain suspended until the employees return to work. He said Marshall has not been suspended or terminated as a result of his recent activities.

Marshall said that he has received widespread support for his protest efforts, and that walkouts were expected to take place Wednesday at the Walmart labs in Portland, Oregon; the Walmart-owned Jet.com e-commerce office in Hoboken, New Jersey; and at his Walmart office location in San Bruno.

Gun control advocates have argued that Walmart should discontinue the sale of all guns and ammunition in the wake of the growing number of mass shootings.