HARRISBURG — Gov. Tom Wolf says at least four children from his state were recently separated from their parents by U.S. Immigration and Customs Enforcement and wrote Monday to demand the agency halt the practice until it has a plan to ensure the welfare of children.

Wolf asked Homeland Security Acting Secretary Kevin McAleenan to account for all children separated from their parents this year in Pennsylvania and to tell him how long they were kept apart and about any steps the federal government took to ensure their well-being.

Wolf said in the letter that the four children are U.S. citizens and come from at least three migrant families. He said that “information relayed” to state officials indicated federal agents did not make sure that the children had adequate temporary guardianship.

An Immigration and Customs Enforcement spokesman in Philadelphia said in an email that any response to Wolf’s letter “would come through the appropriate channels.”

Wolf spokesman J.J. Abbott said the separations occurred in Philadelphia in late July, and at least two of the children have since been reunited with their parents.