An 18-year-old man allegedly carrying a shotgun and running toward the Capitol was arrested by U.S. Capitol Police on Tuesday, the head of the police force said. U.S. Capitol Police Chief Michael Sullivan said the man parked a white Mercedes SUV near the Capitol just after noon and exited the vehicle with the shotgun. He then began running toward the West Front of the Capitol, the side that is adjacent to the National Mall. Asked by a reporter about the suspect's motive, Sullivan said police wer