Sen. Barbara A. Mikulski came to the Secret Service training campus in Beltsville on Wednesday to receive an award. But first the Secret Service put on a quick show for the outgoing lawmaker.
After Mikulski arrived the guests piled outside into the cold and put on protective goggles and earplugs. Soon, sirens blared and a caravan of black SUVs pulled onto a mock downtown street lined by buildings. Then a man started shooting.
The scenario was what the Secret Service calls "attack on principal." That is, an attempt to kill the president.
Agents leapt from cars, rushing to the side of the street with rifles raised. They fired a barrage of shots at the attacker in...