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(NEXSTAR) – Major meat producer JBS USA shut down all of its beef plants in the wake of a cyberattack Sunday, according to the union that represents more than 25,000 JBS meatpacking workers.

United Food and Commercial Workers Union officials told Nexstar Tuesday that all beef plants in the U.S. were shut down and all U.S. meatpacking facilities have seen disruption to their operations.

The plants that were non-operational as of Tuesday are located in Arizona, Texas, Nebraska, Colorado, Wisconsin, Utah, Michigan and Pennsylvania, officials said. The company’s pork plants were still operational as of Tuesday.

Brazilian parent company JBS SA said late Tuesday that it had made “significant progress” in dealing with the cyberattack and expected the “vast majority” of its plants to be operating on Wednesday.

“Our systems are coming back online and we are not sparing any resources to fight this threat,” Andre Nogueira, the CEO of JBS USA said in a statement.

JBS USA officials did not say which U.S. facilities were affected.

Officials with the U.S. Department of Agricultures said in a statement that they have “reached out to several major meat processors in the United States to ensure they are aware of the situation, encouraging them to accommodate additional capacity where possible, and to stress the importance of keeping supply moving.”

The statement continued:

USDA has also been in contact with several food, agriculture and retail organizations to underscore the importance of maintaining close communication and working together to ensure a stable, plentiful food supply. USDA will continue to encourage food and agriculture companies with operations in the United States to take necessary steps to protect their IT and supply chain infrastructure so that it is more durable, distributed and better able to withstand modern challenges, including cybersecurity threats and disruptions.

JBS is the second-largest producer of beef, pork and chicken in the U.S. If it were to shut down for even one day, the U.S. would lose almost a quarter of its beef-processing capacity, or the equivalent of 20,000 beef cows, according to Trey Malone, an assistant professor of agriculture at Michigan State University.

JBS USA said in a statement from Greeley, Colorado, on Monday that it was the target on Sunday of an “organized cybersecurity attack” affecting some of its servers supporting its North American and Australian IT systems.

Malone said the disruption could further raise meat prices ahead of summer barbecues. Even before the attack, U.S. meat prices were rising due to coronavirus shutdowns, bad weather and high plant absenteeism. The U.S. Department of Agriculture has said it expects beef prices to climb 1% to 2% this year, poultry as much as 1.5% and pork between by from 2% and 3%.

White House spokeswoman Karine Jean-Pierre told Reuters during an Air Force One trip to Oklahoma Tuesday that the FBI is investigating and officials have reached out to the Russian government after JBS said they were attacked by a “criminal organization likely based in Russia.”

JBS has more than 150,000 employees and is the largest meat production company in the world.

Earlier in the week the cyber attack caused the shutdown of plants in Australia, where the company has 47 facilities, keeping thousands of workers at home.

The attack is the latest in a series of high-profile ransomware attacks, following the shutdown of the Colonial Pipeline several weeks ago, the temporary outage suffered by Milan-based Campari Group last November and the disruption of Molson Coors breweries in March.

The Associated Press contributed to this report.