There were suggestions the U.S. Capitol Police special operations unit was involved . But internal police sources said that was inaccurate . Snarl of police vehicles , heavy traffic actually prevented the unit from the reaching scene . Officials had said there was initial concern the Capitol might become a secondary target , promoting an increased security presence there . Gunman killed 12 people on July 16 at historic Navy Yard .
There were suggestions the U.S. Capitol Police special operations unit was involved . But internal police sources said that was inaccurate . Snarl of police vehicles , heavy traffic actually prevented the unit from the reaching scene . Gunman killed 12 people on July 16 at historic Navy Yard .