Two Google engineers have quit over the treatment of Timnit Gebru, a prominent Black artificial intelligence researcher whose exit from the company sparked widespread outrage in the tech industry.

David Baker, an engineering director focused on user safety, left Google last month after 16 years because Gebru’s departure “extinguished my desire to continue as a Googler”, he said in a letter seen by Reuters. Baker added: “We cannot say we believe in diversity, and then ignore the conspicuous absence of many voices from within our walls.”

Vinesh Kannan, a software engineer, said on Wednesday that he had also left the company this week because Google had mistreated Gebru and April Christina Curley, a Black recruiter who has said she was wrongly fired from Google last year. “They were wronged,” Kannan said in a tweet.

Gebru, a scientist who is highly respected in her field, has said that she was fired in December after she pushed back on orders to pull research that speech technology like Google’s could disadvantage marginalized groups. Gebru has also said her dismissal followed an internal email in which she expressed frustration over Google’s diversity programs.

Also in December, Curley shared a Twitter thread in which she alleged a number of racist incidents at Google before being fired. She said she had been asked to disclose her Baltimore accent as a disability and was told she was “intimidating” and thus not considered for leadership opportunities.

Google declined to comment but pointed to previous statements that it is looking to restore employees’ trust after Gebru’s departure and that it disputes Curley’s accusation.

The resignations come as workers demand commitments to academic freedom and management change in Google’s research division. For years employee action over discrimination at Google has been mounting.

In November 2018, thousands of employees around the world staged walkouts to protest against sexual harassment and systemic racism. In a complaint filed by the national labor relations board (NLRB) last week, the company was accused of unlawfully surveilling and firing workers who organized protests.

More than 800 people have joined a union announced last month to advance workplace protections, and more than 2,600 of its 135,000 employees signed a December letter supporting Gebru.

“The termination is an act of retaliation against Dr Gebru, and it heralds danger for people working for ethical and just AI – especially Black people and People of Color – across Google,” said the letter, published by the same group that organized a walkout at Google over the company’s treatment of sexual harassment and gender discrimination.

“Research integrity can no longer be taken for granted in Google’s corporate research environment, and Dr Gebru’s firing has overthrown a working understanding of what kind of research Google will permit. This is also a moment of reckoning beyond Google.”

Baker, whose resignation letter was shared with an internal affinity group for Black employees, told Reuters he stood by his remarks. Kannan did not have an immediate comment.