Thomas Marshall, who works in an e-commerce division in San Bruno, California, requested a sick leave general strike in the message he wrote with two employees.
"Of all the arms tragedies, this hits the closest home for many of us," Marshall said. "I felt I had to do something, or else I really wanted to be an accomplice in a company that continued to sell firearms."
Marshall said he sent the message on an internal Slack messaging channel and to an email chain that included approx. 20,000 people.
"In light of recent events and in response to corporate inaction, we are arranging a" sick out "general strike to protest Walmart's profits from the sale of weapons," the letter said, which Marshall also gave to CNN.
"Walmart is a company that has always put its employees and customers first, and we have recently made great strides toward promoting a safe, inclusive and progressive community. Last year, Walmart raised the minimum age to buy a firearm or ammunition from 1
"We have made great strides already, but now we have to orga nize to shape this company into a place we everyone can be proud of. As partners, we have the power, ability and opportunity to change this company for the better. "
Walmart spokeswoman Kory Lundberg said: "We have had no indications of unusual attendance or notice."
He said the company encourages employees to offer suggestions. "There are many more constructive outlets for employees to provide feedback." 
Walkouts, Moment of Stillness Scheduled Wednesday
Marshall said he and colleagues are also arranging a walkout and Moment of Stillness at 3pm local time Monday at facilities across the country.
would include a moment of silence for the victims of the gunfire.
Marshall said he has been working at Walmart for about a year and really likes it.
"We love our employees, we care for each other, and then this really comes from somewhere , we want to change this company to a place we can continue to be proud of, "he said.
He commended the company for the security action it has already done.
Dick's Sporting Goods chain stopped selling assault rifles and high capacity magazines after Parkland, Florida, and fired last year.
Marshall said they would send the Change.org petition, which has more than 32,000 signatures, to Walmart CEO Doug McMillon.
Correction: An earlier version of this story incorrectly stated how many Walmart affiliates might have seen Marshall's Slack message.