MORTON, Miss. — US immigration officials raided several Mississippi food processing plants on Wednesday and signaled that the early-morning strikes were part of a large-scale operation targeting owners as well as employees.

Employees filled three buses — two for men and one for women — at a Koch Foods Inc. plant in tiny Morton, 40 miles (64 kilometers) east of Jackson. They were taken to a military hangar to be processed for immigration violations. About 70 family, friends and residents waved goodbye and shouted, “Let them go! Let them go!” Later, two more buses arrived.

A tearful 13-year-old boy whose parents are from Guatemala waved goodbye to his mother, a Koch worker, as he stood beside his father. Workers who were confirmed to have legal status were allowed to leave the plant after having their trunks searched.

“It was a sad situation inside,” said Domingo Candelaria, a legal resident and Koch worker who said authorities checked employees’ identification documents.

The sting was another demonstration of President Donald Trump carrying out his signature domestic priority to crack down on illegal immigration. Later in the day, he was scheduled to visit El Paso, Texas, where a gunman linked to an online screed about a “Hispanic invasion” allegedly killed 22 people in the border city.

Such large shows of force were common under President George W. Bush, most notably at a kosher meatpacking plant in tiny Postville, Iowa, in 2008. President Barack Obama avoided them, limiting his workplace immigration efforts to low-profile audits that were done outside of public view.

Trump resumed workplace raids, but the months of preparation and hefty resources they require make them rare. Last year, the administration hit a landscaping company near Toledo, Ohio, and a meatpacking plant in eastern Tennessee.

A hangar at the Mississippi National Guard in Flowood, near Jackson, was set up to process employees for immigration violations on Wednesday. There were seven lines, one for each location. Buses had been lined up since early in the day to be dispatched to the plants.

“I’ve never done anything like this,” Chris Heck, resident agent in charge of ICE’s Homeland Security Investigations unit in Jackson, told The Associated Press inside the hangar. “This is a very large worksite operation.”

Koch Foods, based in Park Ridge, Illinois, is one of the largest poultry producers in the US and employs about 13,000 people. The company has no relation to prominent conservative political donors and activists Charles and David Koch.

The company has operations in Mississippi, Alabama, Georgia, Illinois, Ohio and Tennessee. Forbes ranks it as the 135th-largest privately held company in the US, with an estimated $3.2 billion in annual revenue.

The company, which did not immediately respond to a request for comment, said when it received an industry award in February that the Morton plant produces more than 700,000 tons of poultry feed a year.

Agents arrived at the Morton plant, passing a chain-link fence with barbed wire on top, with a sign that said the company was hiring. Mike Hurst, the US attorney for Mississippi, was at the scene.

Workers had their wrists tied with plastic bands and were told to deposit personal belongings in clear plastic bags. Agents collected the bags before they boarded buses.

“This will affect the economy,” Maria Isabel Ayala, a child care worker for plant employees, said as the buses left. “Without them here, how will you get your chicken?”