The U.S. Federal Aviation Administration is indefinitely restricting helicopter flights near Washington Reagan National Airport after a deadly collision between an American Airlines regional jet and Army Black Hawk killed 67 people.

The National Transportation Safety Board said it was too soon to speculate the cause of the deadly crash. Skaters, parents, and coaches from the Skating Club of Boston were aboard the flight.

In the three years before the deadly collision between an Army helicopter and an American Airlines flight near Reagan National Airport, at least two other pilots reported near-misses with helicopters while landing at the airport,