In June, approximately 20 engineers were invited to a meeting at the headquarters of rocket manufacturer SpaceX. Elon Musk, the company’s founder and CEO was the topic of the conversation.

The day before, the company fired five employees who had written a letter urging SpaceX to condemn Mr. Musk’s “harmful Twitter behavior,” in which he used the social network to mock a news report that SpaceX had settled a sexual harassment claim against him. Several engineers entered the meeting expecting a sympathetic ear, as some managers and executives had indicated that they did not approve of Mr. Musk’s behavior.

However, the meeting, which had not previously been reported, quickly became heated, according to two SpaceX employees who were present.

They claimed that Jon Edwards, the meeting’s vice president, described the letter as an extremist act and declared that the writers had been fired for distracting the company and taking on Mr. Musk. Mr. Edwards did not appear to respond when asked whether the CEO could sexually harass his employees with impunity, according to the two employees. However, they claimed that a recurring theme of the meeting was Mr. Musk’s ability to do whatever he wanted at the company.

According to the employees and their lawyers, the SpaceX letter resulted in the firing of nine employees. On Wednesday, eight of those workers filed unfair labor practice charges with the National Labor Relations Board, claiming that their firings were illegal.

The SpaceX case raises new questions about Mr. Musk’s companies’ management practices, where there is little tolerance for dissent or labor organizing.

Tesla, Mr. Musk’s electric car company, has resisted unionization efforts at its factories and is embroiled in a legal battle brought by workers who claim they were not given adequate notice before a layoff in June.

Mr. Musk fired executives and laid off half of Twitter’s 7,500 employees after acquiring the company for $44 billion last month. This week, he had subordinates comb through Twitter employees’ internal communications and public tweets, resulting in the firing of dozens of critics.

Interviews with the eight SpaceX employees who filed the charges reveal Mr. Musk’s firm grip on his workplaces, which extends possibly beyond the bounds of federal law. Six of those employees spoke anonymously for fear of retaliation, and their names are not mentioned in the labor board filings.

Legal experts said the law, which allows employees to band together for “mutual aid or protection,” most likely protected the writing of the letter, which, in addition to addressing Mr. Musk’s online habits, urged SpaceX to more effectively enforce its harassment policies.

Many of SpaceX’s approximately 11,000 employees work there because of the company’s mission. Mr. Musk founded the company in 2002 and it is based in Hawthorne, California. Its goal is to send people to Mars and make humans a “multiplanetary” species.

This mission, however, has been hampered at times by distractions from their CEO, according to interviews with several of the former employees who filed the labor charges. Mr. Musk has openly criticized politicians and government agencies with influence over federal contracts.

In December, a former employee wrote an essay in which she described multiple instances of harassment and groping by coworkers. When she reported the incidents, she said there was little or no follow-up. Following the publication of the essay, other employees began speaking out about what they perceived to be a pattern of predatory behavior by male colleagues.

The company, which does not release employee demographics but is said to be male dominated by employees, has begun an internal audit of its harassment policies, according to The Verge.

Then, in May, Insider reported that SpaceX paid a company flight attendant $250,000 in 2018 after she accused Mr. Musk of exposing himself and proposing sex to her. The story heightened internal tensions, and several employees said in interviews that they were shocked when Mr. Musk made light of the allegations on Twitter.