OpenAI was in open revolt on Monday with 490 employees threatening to leave unless the board resigns and reinstates Sam Altman as CEO, along with cofounder and former president Greg Brockman. Altman was controversially fired by the board on Friday.

“The process through which you terminated Sam Altman and removed Greg Brockman from the board has jeopardized all of this work and undermined our mission and company” the letter reads. “Your conduct has made it clear you did not have the competence to oversee OpenAI.”

Remarkably, the letter’s signees include Ilya Sutskever, the company’s chief scientist and a member of its board, who has been blamed for coordinating the boardroom coup against Altman in the first place.

Shortly before the letter was released, Sutskever posted on X: “I deeply regret my participation in the board’s actions. I never intended to harm OpenAI. I love everything we’ve built together and I will do everything I can to reunite the company.|

The letter’s release follows an extraordinary, head-spinning weekend in Silicon Valley. OpenAI’s board removed Altman from his position on Friday, claiming “he was not consistently candid in his communications with the board, hindering its ability to exercise its responsibilities.”

Mira Murati, OpenAI’s chief technology officer, was appointed as interim CEO.

After blowback from investors including Microsoft, OpenAI’s board seemed open to having Altman return to lead the company. Altman posted a photo of himself wearing a visitors’ badge at the company’s headquarters on Sunday. But last night, the board told staff that Altman would not be returning to the company. Hours later, Microsoft CEO Satya Nadella announced that Altman and Brockman would be joining the tech giant to head a new advanced AI research unit.

In another rapid-fire reshuffle, OpenAI’s board chose to remove Murati and appoint another interim CEO, Emmett Shear, the former CEO of the video game streaming site Twitch.

Some OpenAI staff stayed up all night debating a course of action following news that Altman would not return to OpenAI. Many staff were frustrated about a lack of communication over Altman’s firing.

In their letter, the OpenAI staff threaten to join Altman at Microsoft. “Microsoft has assured us that there are positions for all OpenAI employees at this new subsidiary should we choose to join,” they write.