Several hundred individuals who were arrested during an immigration roundup across Mississippi on Wednesday -- leaving their children without parents in some cases -- have been released, a U.S. Immigration and Customs Enforcement spokesman said Thursday.
Young children were seen crying on local news reports about being separated from their mothers and fathers.
Children of the adults detained in the raids were taken to local elementary schools until they could be reunited with extended family members.
It was the second day of school, Scott County School District superintendent Tony McGee said. Only a couple hours into the day, McGee said that they started receiving reports about what was happening.
"It's tough, it's the second day of school and you're 5-years-old, and you come to school with a mom and dad and all of a sudden you get ready to go home and you don't have one," McGee said.
There were about 15 families in McGee's school district that were affected by Wednesday's operations, he said.
"Nothing prepares you for this," McGee said.
He later added, "It is tough to see small children cry and grown adults who are worried and stricken with grief, trying to reunite those families. And so, 28 years in the business, never had an opportunity to see this and I hope we don't again."
ICE Southern Region Communications Director Bryan Cox defended the agency's handling of the matter on Thursday, saying that as arrests were made, those detained were allowed to make arrangements to have their children picked up and that schools were notified.
Former senior Department of Homeland Security official and current ABC News contributor John Cohen criticized the timing of the operation.
"There was no urgency to conduct this operation and its impact on public safety will be marginal at best," he said.
"For the most part these were not criminals, simply people seeking a better life for their families. There are people who contribute to our economy and are members of the community. In light of the recent mass shootings and other serious threats facing the nation, conducting this operation at this time was at best tone deaf and at worst a questionable use limited law enforcement resources that should be focused on real threats to our security," Cohen continued.
McGee said that the school district is now working to reach out to local immigrant communities to try and make sure people know that schools are a safe place for children.
"Well, what we're trying to do now, is just say, 'Hey, school is a safe place, we're a safe harbor for kids, we want to support you, we're going to love you and we're going to be here for you.' And again, it's not just boys and girls, it's families too," McGee said.
Immigration advocates also condemned the raids, and focused on the children of those set to be deported.
"This is horrifying -- and it's happening right here, right now," the American Civil Liberties Union wrote on Twitterin the wake of the arrests. "America can't be the country we want to live in so long as the president's mass deportation machine is terrorizing our communities and ripping apart families.
(MORE: Thousands protest ICE across cities targeted for weekend raids)Cox said on Thursday that none of those detained remain at a processing center, explaining in an email to ABC News that all have "either been released or custody determination made that they will be held and moved to an ICE detention facility."
Roughly 680 undocumented immigrants were arrested in Mississippi on Wednesday, marking what officials called the largest single-state immigration enforcement in history.
The operations took place at seven work sites -- all agricultural processing plants -- in six different cities, and involved more than 600 agents, according to officials.
Cox said Thursday that more than 300 were released from custody, including approximately 270 released from the processing center, and according to ICE, were "returned to the place where they were originally encountered."
When the individuals who were arrested arrived at the processing center, they were advised to inform ICE officials if they had any children who needed to be picked up, Cox said.
"In order to make it possible for arrestees to contact other family members and address childcare issues, HSI (Homeland Security Investigations) procured cell phones that are available at the processing site for use by arrestees to make arrangements for the care of their children or other dependents," Cox said. "During processing each alien is asked if they have any dependents that need to be cared for. Any arrestee who identifies a child care issue, and is not being criminally arrested or is subject to mandatory detention, will be expeditiously processed and returned to the point of apprehension so that they can get to their child or other dependents."
Cox said that when the operation ended, two HSI officials contacted schools in the area to notify them that there were operations taking place and to provide contact information if the schools found that there were any children whose parents did not pick them up.
According to an ICE news release, "As part of HSI procedures pursuant to this operation, if HSI encountered two alien parents with minor children at home, HSI released one of the parents on humanitarian grounds and returned that individual to the place from which they were arrested. HSI similarly released any single alien parent with minor children a home on humanitarian grounds and physically returned that person to the place where he or she was originally detained. Based on these procedures, it is believed that all children were with at least one of their parents as of last night."
Also, there were approximately 30 people at the plants where the raids took place who were not transported due to humanitarian factors. This could include things like pregnancy, nursing mothers, Cox said, but added that it's case-by-case.
(MORE: ICE raids across major US cities fall short of expectations but fear remains)At a Wednesday news conference, officials said they began preparing for the raids over a year ago.
"The arrests today were the results of a year-long criminal investigation and the arrests and warrants that were executed today are just another step in that investigation," ICE acting Director Matthew Albence said, explaining that each case would be handled individually.
"Our arrests of these individuals is the front end of the process, we will process them, we will place them in front of an immigration judge where they will make their case as to whether or not they have a lawful right to remain in the country. The judge ultimately makes the decision as to whether or not these individuals can stay. If the judge orders them removed, then we will execute those removal orders on the back end of the process," Albence said.
Three of the seven raids took place at Peco Foods facilities in Mississippi.
"We can confirm the Department of Homeland Security was on-site at three of our facilities in Mississippi this morning -- Bay Springs, Canton and Sebastopol," the company said in a statement. "We are fully cooperating with the authorities in their investigation and are navigating a potential disruption of operations."
When asked if there was concern over carrying out these raids as communities continue to mourn over two mass shootings that took place over the weekend, including in the border town of El Paso, Texas, Mike Hurst, U.S. attorney for the Southern District of Mississippi, said that although what happened was "horrific," the immigration enforcement operations had been planned for several months prior to the incidents that occurred last weekend.
"This operation began over a year ago, you don't bring over 650 special agents from around the country into the Southern District of Mississippi in a matter of three days without preparation for months and months and months. So while the tragedies on Saturday and this weekend around the country are horrific, this operation had been planned way before that and we intended to carry it out," he said.