SAN FRANCISCO -- Sam Altman, a prominent executive behind the rise of artificial intelligence, was hired by Microsoft days after being ousted as CEO of OpenAI, eliciting a letter signed by nearly 600 employees at OpenAI calling for the resignation of the company's board and the return of Altman.
The employees threatened to quit and join Microsoft if their demands were not met, according to a copy of the letter obtained by ABC News. Included among the signees was company board member Ilya Sutskever as well as Mira Murati, who briefly served as interim CEO after the departure of Altman.
The letter, addressed to OpenAI board members, says: "Your conduct has made it clear you did not have the competence to oversee OpenAI."
"We, the undersigned, may choose to resign from OpenAI and join the newly announced Microsoft subsidiary run by Sam Altman and Greg Brockman," the OpenAI employee letter said. "Microsoft has assured us that there are positions for all OpenAI employees at this new subsidiary should we choose to join. We will take this step imminently, unless all current board members resign, and the board appoints two new lead independent directors."
Greg Brockman, the former president of OpenAI who resigned from the company soon after the departure of Altman, will also join the newly created AI team at Microsoft.
"We look forward to moving quickly to provide them with the resources needed for their success," Nadella said on X in an announcement of the hiring of Brockman and Altman.
In a repost of the announcement from Nadella, Altman said on X: "The mission continues."
In a separate post, Brockman announced the leadership of the new AI department at Microsoft, which appeared to include several recent employees at OpenAI. "We are going to build something new & it will be incredible," Brockman said.
Meanwhile, OpenAI hired former Twitch CEO Emmett Shear as its interim CEO, replacing executive Mira Murati days after internally appointing her to the role, Shear said Monday on X.
The departure of Altman from OpenAI followed a review process undertaken by the company's board of directors, according to OpenAI, the maker of the popular conversation bot ChatGPT. The review concluded that Altman "was not consistently candid in his communications with the board," OpenAI said in a statement on Friday.
One of the board members involved in the exit of Altman, however, has since expressed remorse about the move.
"I deeply regret my participation in the board's actions," Sutskever, a longtime AI researcher and co-founder of OpenAI, posted on X on Monday. "I never intended to harm OpenAI. I love everything we've built together and I will do everything I can to reunite the company."
In January, Microsoft announced it was investing $10 billion in OpenAI. The move deepened a longstanding relationship between Microsoft and OpenAI, which began with a $1 billion investment four years ago. Microsoft's search engine, Bing, offers users access to ChatGPT.
OpenAI has risen to prominence since ChatGPT was made available to the public a year ago. The chatbot now boasts more than 100 million weekly users, Altman announced earlier this month.
Speaking with ABC News' Rebecca Jarvis in March, Altman said AI holds the capacity to profoundly improve people's lives but also poses serious risks.
"We've got to be careful here," Altman said. "I think people should be happy that we are a little bit scared of this."
ABC News' Zunaira Zaki contributed to this report.