At least three employees at Amazon’s fulfillment center in Shakopee have now tested positive for COVID-19, the company has told employees in recent days, sparking increased concerns among some workers who have been clamoring for more protections and safety measures.

After the company disclosed the second coronavirus case, at least 25 Amazon workers in Shakopee walked off their shift to demand an extension of unlimited unpaid time off for workers who don’t feel safe working or need to stay home during the pandemic. In addition, they protested what they said were unjust firings of multiple workers.

In the most recent case, workers said Faiza Osman had been fired for issues related to taking unpaid time off.

“That was the spark,” said Hafsa Hassan, a worker who took part in the walkout.

It appears the company was reinstating Osman. An Amazon spokeswoman did not provide details but said that Osman is still employed by the company.

Hassan said workers have been on edge about their safety and worried about transparency on how many COVID-19 cases there may be. Workers had seen one employee’s area being sprayed down on Friday, then received notification about another positive case the next day, she said.

A couple weeks ago, another worker at the Shakopee warehouse, Bashir Mohamed, who had been circulating petitions and raising concerns about safety issues, was fired. He claims he was targeted because of his activism. But Amazon said he was fired “as a result of progressive disciplinary action for inappropriate language, behavior and violating social distancing guidelines.”

His dismissal, as well as that of another unnamed worker, prompted Rep. Ilhan Omar, D-Minn., to send a letter to the Occupational Safety and Health Administration requesting a “comprehensive investigation” into the firings at the Shakopee center.

There have been a handful of other cases nationwide in recent weeks of outspoken Amazon employees being fired for various reasons.

“We respect the rights of employees to protest and recognize their legal right to do so,” Amazon has said. “However, these rights do not provide blanket immunity against bad actions, particularly those that endanger the health, well-being or safety of their colleagues.”

Small protests have been held outside of Amazon warehouses around the U.S. in the past month or so as workers have asked for increased protections. At the same time, Amazon has been hiring tens of thousands of temporary workers to help keep up with the surge of online orders.

A few weeks ago, the Minneapolis-based Awood Center, a workers’ advocacy group, filed an OSHA complaint and called on Amazon to temporarily close its warehouse in Shakopee after it learned of what it said was a likely COVID-19 case. Amazon at the time said it was not aware of any positive cases at that facility.

Over the weekend, workers in Shakopee said they received text messages from the company on Friday, Saturday and Sunday notifying them of new cases.

The texts said the three infected workers’ last days in the building were on April 15, 20 and 24.

On Monday, Amazon would not disclose how many cases have been at the Shakopee fulfillment center, but said there were some.

“We are supporting the individuals who are recovering,” Lisa Levandowski, an Amazon spokeswoman, said in a statement. “We are following guidelines from health officials and medical experts, and are taking extreme measures to ensure the safety of employees at our site.”

Amazon said it has been notifying employees of positive cases and giving workers diagnosed with the virus up to two weeks of pay. Those who may have come in close contact with the employees are being paid while self-quarantining for 14 days.

The company has extended the hazard pay of an additional $2 an hour it is paying workers, as well as double pay for overtime during the pandemic, until May 16. While Amazon had been letting employees take unlimited paid leave, workers will have to start applying for a leave in May. Levandowski said Amazon’s leave of absence options will be available for workers who are considered high-risk for the coronavirus or may need to stay home because of school closings.

While Hassan and Awood Center said more than 50 workers had taken part in Saturday night’s walk out, Amazon said it was about half that many.

During the pandemic, Amazon has stepped up cleanings of its facilities, instituted social-distancing measures, required employees to wear masks in warehouses and is taking employees’ temperatures at the start of shifts.