According to Reuters, 153 workers at the plant tested positive for coronavirus. The United Food and Commercial Workers union, who represent the workers, say that measures to control the outbreak in the plant were not working.

The outbreak has hit over 10 percent of the workforce at the Smithfield-owned Farmer John plant, said John Grant, president of the local chapter of the UFCW.

"It's dangerous and the problem with this is that it's invisible, insidious and deadly," Grant said. "And so what you do is when a shark is in the water, you pull everyone out of the water and you make an assessment of what is going on. That's what has to happen right now, a sharp honest assessment of what is going on."

Smithfield, owned by China's WH Group Ltd, said in a statement it has "implemented aggressive measures" to protect workers' health and safety, including temperature scanning, free voluntary COVID-19 tests, more personal protective equipment and plexiglass barriers on the production floor.

Meatpacking plants have proved devastatingly effective vectors of the coronavirus across the United States. About 30 plants temporarily closed in Nebraska, Iowa, Minnesota and several other Midwestern states last month, according to the UFCW.

Pork and beef slaughter capacity have dropped by 30 percent to 40 percent, according to the USDA. To avoid a further decline in a major food supply, President Donald Trump at the end of April ordered meat plants stay open during the pandemic.

Los Angeles County Commissioner Hilda Solis said in a statement the county has asked the Smithfield plant to provide a report by next week detailing its COVID-19 mitigation plans and what it is doing to provide support for the plant’s "workers, their families, and the surrounding Southeast Los Angeles communities."

Read more about this story on Reuters.