Two intruders have been arrested after entering an office building belonging to the US House of Representatives with a toy gun, police said. The two, a man and a woman, entered the Cannon Office Building, which contains offices for US congressmen, at 13.00 local time.As they went through the checkpoint, metal detectors spotted a suspicious object in the man's backpack. But before police could stop them, they grabbed the bag and ran down a corridor. The six-storey building was sealed off and evacuated while police carried out a floor-by-floor search.