CHICAGO >> Chicago’s aviation department says one of its police officers involved in dragging a man off a United Airlines flight at O’Hare International Airport did not follow standard operating procedures and has been placed on leave.

The department said in a brief statement today it did not condone the aviation security officers’ actions Sunday night.

The statement did not release the officer’s name and it was not immediately clear which of the three men seen in the now-widely seen video taken by another passenger was placed on leave.

United has said that the incident came after the flight to Louisville, Kentucky, was overbooked and airline officials asked for volunteers to get off the plane. When none of them did, the airline told four passengers who were selected at random that they had to get off the plane. Three of them did but the fourth refused. United called the airport police, who came aboard the plane and dragged him away.