I just read two interesting pieces in responsible newspapers on this subject. One, the Houston Chronicle said that a year ago, the controller on duty at DCA was locked out and two jets landed using uncontrolled airport procedures.
Another was an interview with an aviation lawyer...he, in the Washington Post, said the pilots followed the proper protocols and landed safely.
He also went further to say that some secure procedures, not available to the general public due to security concerns, allowed the tracon controller to proceed as he did.
I encourage you to go to google news dot com, search reagan national airport and try to find the articles.