https://www.youtube.com/watch?v=URhrRd4ag38

In tearful videos and images that ricocheted across social media, children whose migrant parents were rounded up by federal authorities in Mississippi pleaded with the United States government to release their mothers and fathers.

“Government, please show some heart,” begged an 11-year-old girl whose father was apprehended Wednesday in targeted immigration raids that the authorities said were the largest ever in a single state.

Dozens of children, some as young as toddlers, were bewildered when they were picked up from school and taken to makeshift shelters. Videos showed children crying in corners or in the arms of friends, neighbors and strangers. On Thursday afternoon, state officials, immigration advocates, and lawyers still did not have a clear picture of what happened to those children, or who took custody of them.

The Mississippi Department of Child Protection Services said that no child was in its custody.

“We have no idea what the number of children is, or where they are,” said Lea Anne Brandon, an agency spokeswoman.

Ms. Brandon said the department, which was not notified in advance of the raids by federal officials and still knew nothing on Thursday, learned of the sting operation from news reports on Wednesday.