Multiple Amazon employees were hospitalized after being exposed to an unknown substance at a distribution center in southern California, as per a report.

Amazon Warehouse Evacuated Over Hazmat Scare, Multiple Workers Hospitalized
Warehouse Workers For Justice Hold Press Conference On Injury Rates At Chicago Area Amazon Warehouses CHICAGO, ILLINOIS - DECEMBER 10: Former injured Amazon employees join labor organizers and community activists to demonstrate and hold a press conference outside of an Amazon Go store in the loop to express concerns about what they claim is the company's "alarming injury rate" among warehouse workers on December 10, 2019 in Chicago, Illinois. According to the community group Warehouse Workers for Justice, some Amazon warehouse facilities have injury rates more than twice the industry average, with peak rates occurring during the holiday season. Scott Olson/Getty Images

According to Fox News, on Saturday afternoon, Amazon warehouse evacuated, and multiple workers were hospitalized over potentially hazardous material. Jody Hagemann, a spokeswoman for Cal Fire/Riverside County Fire, said, "They were exposed to an unknown substance inside the building, The Press-Enterprise in Riverside, east of Los Angeles, says.

The news outlet reported that Hagemann said the substance had not yet been isolated. At the Amazon Fulfillment Center in Eastvale, west of Riverside, approximately 150 employees evacuated. At least six individuals were taken to the hospital for manifesting mild to moderate symptoms, the Cal Fire/Riverside County Fire Department said in a statement posted on Twitter.

The HAZMAT crew were unable to find the dangerous substance after they entered the building. The warehouse would shortly reopen for normal operations, Cal Fire said.

The fire department and Amazon have been contacted for comment. The incident happened weeks after Amazon was fined for COVID-19 safety violations at its two warehouses.

The Amazon delivery center in Hawthorne and the Eastvale fulfillment center was being investigated by California's Division of Occupational Safety and Health following complaints from the employees regarding their conditions amid the pandemic, The Los Angeles Times reported.

The employees claimed that Amazon did not correctly implement social distancing and did not stop cleaning and disinfection operations of the warehouses where infected workers spent their shifts, Newsweek via MSN reported.

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Facilities failed to mitigate workers' exposure to the COVID-19, investigators found, by not giving practical safety training and was fined the company around $1,500. The October 6 citations said that the employer didn't ensure all workers had access to, understood, and viewed all COVID-19 training materials. Besides, employees were unaware of the training materials' critical elements, such as sanitation of frequently touched objects and workstations in the workplace.

Amazon revealed early last month that almost 20,000 Amazon and Whole Foods Market front-line workers across the U.S. tested positive or presumed positive for the coronavirus as of late September.

The company announced this week that it plans to hand out bonuses worth more than $500 million to the U.S.employees for the upcoming holiday season.

Amazon workers are staging Black Friday protests

Thousands of people worldwide are protesting against Amazon's facilities while the company gears up for one of its most important days of the year. On Friday, Human-rights organizations, a coalition of unions, and environmental groups launched a global protest of the so-called "Make Amazon Pay."

According to Business Insider via MSN, the organizations gave a list of wide-ranging demands, such as raising warehouse workers' benefits and pay, committing to ending Amazon's contracts with fossil-fuel industries and ending union-busting tactics.

In March, Amazon workers received a $2 wage increase per hour that was then cut in summer. Its online sales skyrocketed amid the COVID-19 pandemic, and its revenue is projected to soar higher with the holiday season.

Read also: Lawmakers Say Amazon Exercised Monopoly Power Over Third-Party Sellers