Two students were with the adult outside the Southwest Side school Wednesday morning, officials said. "It is really terrifying for families and traumatizing for students," one observer said.

Acero Schools officials say the adult was picked up with two children in their car. U.S. Immigration and Customs Enforcement officials did not immediately confirm the action.

The Chicago Teachers Union said a father was arrested by immigration agents Wednesday morning as he was dropping off his kids at a charter school in the Gage Park neighborhood. A community member sent a video showing the moments Acero Schools said an adult was detained by U.

Immigration officials allege that the man, who had two students in the car with him, has criminal convictions and was twice previously removed from the country.

In a letter to families Wednesday, officials with the Acero charter school network said the individual was taken into custody by ICE agents, though the agency itself did not respond to a request for comment.