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Private rocket company SpaceX has fired an unspecified number of employees who contributed to an open letter that condemned the behavior of CEO and founder Elon Musk.

In an email to staff, SpaceX President Gwynne Shotwell said the company had investigated and "terminated a number of employees involved" in writing and distributing the letter. Reuters reported that at least five employees have lost their jobs.

The letter—which called Musk's antics "a frequent source of distraction and embarrassment—was addressed to SpaceX executives. It asked them to publicly condemn Musk's recent statements on Twitter, explicitly separate SpaceX from the CEO's personal brand, and establish protocols for reporting and dealing with inappropriate behavior by executives and employees.

Shotwell said the company dismissed employees because the letter had caused other workers to feel "uncomfortable, intimidated and bullied, and/or angry because [it] pressured them to sign onto something that did not reflect their views."

One LinkedIn user, Brian Watkins, founder of BTOM Consultants, scoffed at that explanation.

"Does no one think that firing people for being critical will make employees feel uncomfortable, intimidated or bullied?" he asked in his post.

"Musk has spoken out that the reason he wants to own Twitter is to let people say what they want as long as it is legal," he continued. "Evidently, that doesn't apply when it is directed at him. Sounds like the exact opposite of psychological safety."

Musk is moving toward completing his $44 billion purchase of Twitter. He addressed Twitter employees for the first time via a video call on Thursday.

It is unclear how many of SpaceX's 12,000 employees signed the open letter. The Hawthorne, California-based company has about 12,000 employees. Its website lists about 900 open positions.

SpaceX did not immediately respond to Law.com's request for comment.

The open letter, which was first reported by The Verge on Thursday, follows a torrent of tweets from Musk in recent months that have raised eyebrows. In addition, last month  Business Insider reported that SpaceX paid $250,000 in 2018 to settle claims that Musk exposed himself to a flight attendant on a private jet.

Musk has denied the allegation. A day after doing so, he tweeted Tesla was building a litigation department. "Looking for hardcore streetfighters, not white-shoe lawyers … who thrive on corruption. There will be blood."