US immigration officials raided numerous Mississippi food processing plants and arrested 680 people, mostly Latino workers, on Wednesday in the largest workplace sting in at least a decade.

The raids took place just hours before Donald Trump was scheduled to visit El Paso, Texas, the majority-Latino city rocked by the recent mass shooting that left 22 people dead. The suspected killer in that attack was linked to an online screed about a “Hispanic invasion”, in language that echoed Donald Trump’s rhetoric on immigration.

Bill Chandler, president of the Mississippi Immigrant Rights Alliance, told the Jackson Free Press he is in touch with schools, where children may have been left behind on Wednesday after Immigration and Customs Enforcement (Ice) federal agents detained their parents. He added that Ice agents attempted to arrest at least one American citizen.

At a Mississippi school, the children and family members of immigrants plucked out of their workplaces by federal agents in today’s historic #ICEraids weep, unsure when or if they’ll see their loved ones again. Their back to school week. Shared with permission from Miriam Sanchez pic.twitter.com/0vr3CEWPTj — Ashton Pittman (@ashtonpittman) August 7, 2019

The raids left local communities to pick up the pieces after children were separated from their parents by the raids on the first day of the new school session after the summer break. In Forest, Mississippi, one local news report found children were left without a place to stay when they were locked out of their homes, and were forced to sleep in a local gym.

“Let my parent be free with everybody else,” 11-year-old Magdalena Gomez Gregorio said into a WJTV camera, sobbing, as other children could be seen in tears. “I need my Dad by me, my Dad didn’t do nothing, he’s not a criminal,” she said. A godparent of some of the children affected by the crackdown said many of the adults detained had been in the US for many years and did not have criminal records.

Vigils mourning the deaths in El Paso took place around the country on Wednesday evening, as well as for the eight people killed in a shooting in Dayton, Ohio, on Sunday, both of which have led to calls for greater gun control and an end to racist political rhetoric.

At the same time as Mississippi communities were attempting to find shelter for children left parentless by the raids.

United We Dream, the largest youth-led immigrant rights group in the US, called the raids an act of white supremacy that “deliberately targeted small towns with little resources for protection”.

The group added: “Tonight, hundreds of children will go to bed separated from their families, not knowing when or if they will be reunited. This is an act of terrorism.”

Local advocates also decried the raids as “political grandstanding”.

“Nobody in Mississippi who I know is crying out for hundreds of out-of-state agents to invade Mississippi and haul off our hardworking neighbors and friends in zip ties and buses,” Cliff Johnson, director of the MacArthur Justice Center at the University of Mississippi School of Law, told the Jackson Free Press.

Workers filled three buses – two for men and one for women – at a Koch Foods plant in the tiny city of Morton, 40 miles (64km) 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. Some employees tried to flee on foot but were captured in the parking lot.

HAPPENING NOW: In Forrest, Mississippi where one of the #ICE raids happened nearby Children of those who were arrested are left alone in the streets crying for help. Strangers and neighbors are taking them to a local gym to be put up for the night. FULL STORY TONIGHT ON @WJTV. pic.twitter.com/s2zuTTRYfM — Alex Love (@AlexLoveWJTV) August 8, 2019

Workers who were confirmed to have legal status were allowed to leave the plant, after Ice agents searched their trunks.

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

The company did not immediately respond to an emailed request for comment.

Friends, co-workers and family watch as US immigration officials raid a Koch Foods plant in Morton. Photograph: Rogelio V Solis/AP

Mississippi is the country’s fifth-largest chicken-producing state and the plants’ tough processing jobs have mainly been filled by Latino immigrants eager to take whatever work they can get.

At a press conference, Mike Hurst, the US district attorney for the southern district of Mississippi, warned business owners not to employ undocumented immigrants. “If we find that you have violated federal criminal law, we’re coming after you,” Hurst said.

Matthew Albence, Ice’s acting director, said the raids, which involved about 600 agents, could be the largest such operation thus far in any single state.

Such large shows of force were common under George W Bush, most notably at a kosher meatpacking plant in tiny Postville, Iowa, in 2008. Barack Obama avoided the tactic.

Two people are taken into custody at the plant. Photograph: Rogelio V Solis/AP

Trump resumed workplace raids. Last year, the administration hit a landscaping company near Toledo, Ohio, and a meatpacking plant in eastern Tennessee.