Amazon has fired two Seattle-based employees who publicly criticized safety and working conditions at its warehouses during the COVID-19 pandemic, The Washington Post reports. User experience designers Emily Cunningham and Maren Costa were both fired on Friday after they tweeted criticism of the company, and offered to match donations to warehouse workers. Both had also previously criticized Amazon’s climate policies.

A third employee, Chris Hayes, was asked not to return to work after he circulated an invitation to join a virtual discussion with warehouse workers, The New York Times reports. Hayes had handed in his notice at the company over its treatment of the workers and was due to leave on April 17th, but was told he would no longer be allowed to work after sending out the invitation on Friday.

Amazon previously fired an employee who helped to organize a walkout

Amazon has faced fierce criticism over working conditions at its warehouses during the COVID-19 pandemic. While its warehouses are continuing to operate — and expand by 175,000 new hires — to fulfill orders while people are stuck at home, warehouse workers have complained that they haven’t been given enough protective equipment to keep them safe and that the company hasn’t been proactive enough at notifying workers when their colleagues test positive for the virus. Amazon has been addressing the issues, but the implementation of its new safety precautions has been uneven.

These are not the first employees to have been fired after criticising Amazon’s response to the pandemic. Last month Amazon fired Chris Smalls, a warehouse worker who helped to organize a walkout at the company’s Staten Island, New York, fulfillment center. Amazon said that it fired Smalls for violating safety regulations. However, subsequent reports suggested that Amazon planned to publicly smear Smalls and discredit the labor movement within the company. New York Attorney General Letitia James said that the firing was “disgraceful” and called for an investigation by the National Labor Relations Board, The Washington Post notes.

As well as the public tweets, Cunningham and Costa also circulated a petition internally calling for improved sick leave policies, hazard pay, and child care for warehouse workers, according to The New York Times.

Cunningham and Costa had both previously criticised the company over its climate policies, and both were members of the climate group, “Amazon Employees for Climate Justice.” Last October a statement attributed to Costa was published by The Washington Post which said that “Amazon wants to profit in businesses that are directly contributing to climate catastrophe.” She says she was later called into a meeting with human resources and told she could lose her job if she broke the company’s communications policy again.

Amazon’s communication policy says that employees need executive approval or a corporate justification if they want to comment publicly on its business, The Washington Post reports.

In a statement, a spokesperson from Amazon confirmed that the employees were fired for “repeatedly” violating the company’s policies. “We support every employee’s right to criticize their employer’s working conditions,” a spokesperson said, “but that does not come with blanket immunity against any and all internal policies.”