The Communications Workers of America has filed a federal labor charge against Alphabet Inc’s Google. In that, it is accusing the company of unlawfully firing four employees to deter workers from engaging in union activities. The four employees include Rebecca Rivers, Laurence Berland, Paul Duke, and Sophie Waldman.

The complaint will now trigger a National Labor Relations Board (NLRB) investigation into whether Google violated the four individuals’ right to raise concerns about working conditions.

When violations are found in such cases, the NLRB typically tries to help accusers and companies reach a settlement. Google had previously said that the four workers were let go last month for violating the company’s data-security policies.

The CWA union, which represents 700,000 workers across several industries in North America, has been trying to organize workers at Google. Laurie Burgess, an attorney at Messing Adam & Jasmine, said the union stepped forward to make the charge against the company “because it has been harmed by Google’s actions.”

The filing says that Google investigated and fired the four employees “to discourage and chill employees from engaging in protected concerted and union activities. Its actions are the antithesis of the freedoms and transparency it publicly touts.”

Since last year, the search engine giant has reeled in elements of its unorthodox culture. The company, dealing with much broader influence, will now be cutting back on companywide meetings from next year.

Google’s decision to fire these organizers is stirring up worker dissent within the company’s rank and file. This is adding to growing political tension within the company that’s only seems to be getting worse.