Mississippi residents have rallied around terrified children left behind after their parents were arrested in the United States’ largest immigration raid in a decade.

A total of 680 people were arrested in Wednesday’s raids, but more than 300 had been released by Thursday morning, US Immigration and Customs Enforcement spokesman Bryan Cox said in an email.

Mr Cox said 30 of those who had been released were let go at the plants, while about 270 were released from a military hangar where they’d been taken after the raids.

He said people were let go due to “humanitarian factors.”

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

“They were placed into proceedings before the federal immigration courts and will have their day in court at a later date,” he said.

On Wednesday, about 600 US Immigration and Customs Enforcement agents fanned out across plants operated by five companies, surrounding the perimeters to prevent workers from fleeing.

Children of those who were arrested in the #ICEraids are left alone in the streets crying for help. Don’t look away. https://t.co/1iMLVFz8of

— Alyssa Milano (@Alyssa_Milano) August 8, 2019

One of the targeted companies was poultry producer, Koch Foods Incorporated. in Morton, a small town about 65 kilometres east of the capital of Jackson.

Workers at Koch were loaded into multiple buses on Wednesday. At one point, about 70 family, friends and residents waved goodbye and shouted, “Let them go! Let them go!”

Koch Foods said on Thursday it follows strict procedures to make sure full-time employees are eligible to work in the country.

The Mississippi Department of Child Protection Services is investigating whether any immigrant children are in need of foster care while their parents are in detention.

-AAP