Thomas Marshall, a 23-year-old category manager at Walmart in San Bruno, California, sent out an email urging his co-workers to stage a sick-out general strike to protest the retailer's gun sales. Walmart, one of the largest gun and ammunition retailers in the world, was the scene of two shootings last week, including the xenophobic attack in El Paso which left 22 people dead and more than two dozen injured. 

Marshall used internal Slack channels and an email chain that included 20,000 employees to encourage his coworkers to call in sick on Tuesday, take part in a walkout Wednesday, and sign a Change.org petition in protest of Walmart's gun sales. As of Thursday, the petition, directed at Walmart CEO Doug McMillon, has nearly hit its target of 50,000 signatures. 

"Of all the gun tragedies, this hit the closest to home for a lot of us," Marshall told CNN. "I felt like I had to do something or else I would really be complicit in a company that was continuing to sell firearms." He told NBC News that he's willing to risk his job in order to take a stand against the chain retailer, as his work account was temporarily suspended after he attempted to organize the protests. 

In 2015, Walmart stopped selling assault-style rifles and last year it banned the sale of firearms to anyone under the age of 21 after the mass shooting in Parkland, Florida. Despite these reforms, half of the 4,700 Walmarts in the country still sell guns, and many more sell ammunition, according to company spokesperson Randy Hargrove. "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."

According to Reuters, approximately 40 Walmart employees in San Bruno, California participated in the walkout on Wednesday, but according to Marshall, many workers feared the company would retaliate should they participate in protests.