I was in the US Marine Corps in 1962-64, stationed at the Marine Barracks, 8th &I. We were called out several times for riot control. During the Kennedy funeral things started getting out of hand on the parade route on Penn Ave. Crowds started moving into the street behind the caisson carrying Kennedy. We had trained and were deployed all the way across the street, shoulder to shoulder wall to wall, fixed bayonets held at the ready chest high on the advancing mob. That put a stop to it in jig time.
A lot of people don't know that Washington, DC is contained inside The Military District of Washington. Washington is not a state, so the military can be deployed there for law enforcement purposes. I rest assured that the Marines, Army, Navy, Air Force and Coast Guard will all be on the alert, equiped with gas masks and what ever wepons are needed to control crowds, and well trained to deal with it.