A collision between an American Airlines passenger jet and an Army helicopter at Ronald Reagan Washington National Airport near Washington, D.C, killed 67 people, including more than a dozen figure skaters.

A midair collision between a U.S. Army helicopter and an American Airlines flight killed all 67 people aboard the two aircraft, officials said Thursday as they scrutinized the actions of the military pilot and reported that control tower staffing was “not normal” at the time of the country’s deadliest aviation disaster in almost a quarter century.