When the jetliner crashed into the Pentagon on Sept. 11, 2001, Cathy Lanier was a district commander trying to make sense out of the chaos.

The Metropolitan Police Department was getting much of its information from the media, officers were uncertain whether there would be more attacks, and traffic was jammed so much that even with sirens blaring and sometimes driving up on the curb, it took Lanier an hour to travel a few miles from headquarters to her District 4 command office in Columbia Heights.