Thousands of workers at Salesforce are pressing the software company to cut ties with the National Rifle Association after a mass shooting at an elementary school in Uvalde, Texas, left 21 people dead.

At least 4,000 employees at the San Francisco-based company signed an open letter to co-CEOs Marc Benioff and Bret Taylor urging them to cease doing business with the NRA, SFGate first reported. The NRA uses Salesforce products for marketing and fundraising purposes, according to the letter. 

“It’s not in our power to get background checks or other gun control measures passed by Congress — but we can effect change by ending our commercial relationship with our customer, the National Rifle Association,” the employees stated, according to Protocol, which obtained a copy of the letter. They also said it is “unconscionable” that the NRA uses Salesforce’s products to further its agenda. 

Benioff is an outspoken advocate for gun control, calling for a ban on AR-15-style rifles in a 2018 tweet. On May 25, the day after the shooting in Uvalde, Benioff told CNBC that corporate leaders “need to take direct action” on social issues like gun control and abortion rights. 

“I’m surprised that action has not been taken. There are too many words and not enough actions,” he said, adding that companies need to stand up for their values. 

Salesforce did not immediately reply to a request for comment. 

Companies have previously distanced themselves from the NRA in the aftermath of mass shootings. Several businesses, from insurers to software companies to airlines, ended partnerships with the gun rights advocacy group following a mass shooting at a high school in Parkland, Florida. 

The NRA Business Alliance comprises hundreds of companies across the automotive, construction, legal, retail and other industries. The gun rights group promotes member businesses through its marketplace. 

Boats Unlimited, a boat parts sales and storage outfit in Utica, New York, said the Uvalde massacre will have no effect on its relationship with the NRA. When asked by CBS MoneyWatch if he was considering cutting ties with the group, owner Mike Clare said, “never.” 

“There is no blame to place on the NRA or any NRA member or gun owner,” he said. “We support the NRA and they support us.”