A group of Tesla workers in Buffalo, New York, have accused the company of firing more than 30 people to try to quash the campaign. They have filed a complaint with the National Labor Relations Board.

In the press release, the group that calls itself Tesla Workers United, accuses Tesla and CEO Elon Musk of retaliating in direct response to the unionization drive, launched on February 14 at Tesla’s Buffalo Gigafactory 2.

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The affected employees are part of the Buffalo facility’s autopilot group, where they train Tesla’s artificial intelligence software by identifying images. The group is seeking a federal injunction to protect the workers’ rights.

The union drive is being led by the Rochester, New York-based unit of Workers United, which is an affiliate of the larger Service Employees International Union. Workers United is also the group that has been trying to organize Starbucks locations.

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The Rochester Regional Joint Board of Workers United helped workers at Tesla Gigafactory to form a group called Tesla Workers United. It aims to make the Buffalo factory Tesla’s first union shop. The union says Tesla committed unfair labor practices by firing the workers and is seeking injunctive relief from NLRB.

On Thursday, Tesla Workers Union said they remain undeterred in their union drive.

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“We’re angry. But this won’t slow us down or stop us,” the group wrote on Twitter. “They want us to be scared, but they just started a stampede. These firings are the exact reason why we need a union @tesla. We believe we can do this, but more importantly, we believe we WILL do this,” it added.

The National Labor Relations Board (NLRB) has the authority to order an employer to reinstate workers with back pay but it cannot assess penalties.

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Previously, Tesla has been accused of illegally firing union supporters at its plant in California, it’s first to build cars but efforts to organize that plant have fallen short of the union’s filing to hold votes among employees there.

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Several times Musk criticized unions in tweets, one of which the NLRB ordered him to delete three years after it was posted. Tesla has disbanded its public relations staff and has not responded to press inquiries for many years.