The letter criticized Elon Musk’s public behavior.

Yesterday, a small coalition of SpaceX employees circulated an open letter within the company, sending it primarily to several of the company’s executives. The letter outlined various concerns and grievances the employees had with the attitude and conduct of the company’s founder and CEO, Elon Musk.

“Elon’s behavior in the public sphere is a frequent source of distraction and embarrassment for us, particularly in recent weeks,” a passage from the letter, obtained by The Verge, reads. “As our CEO and most prominent spokesperson, Elon is seen as the face of SpaceX — every Tweet that Elon sends is a de facto public statement by the company. It is critical to make clear to our teams and to our potential talent pool that his messaging does not reflect our work, our mission, or our values.” The letter also called for the company to “publicly address and condemn Elon’s harmful Twitter behavior.”

This morning, several company insiders revealed to CNBC that at least five of the employees that signed the open letter had been terminated from the company.

In an email to The New York Times, SpaceX president Gwynne Shotwell explained why the employees were let go. “The letter, solicitations and general process made employees feel uncomfortable, intimidated and bullied, and/or angry because the letter pressured them to sign onto something that did not reflect their views,” wrote Shotwell. “We have too much critical work to accomplish and no need for this kind of overreaching activism.”