There has been an explosion of some sort near the White House, apparently a small one. I'm at a conference about one block from the White House and arrived at 9 AM. Half the people who were supposed to attend have not been able to get here. Those arriving report 17th Street closed traffic and other areas blocked off. Someone said they heard a transformer exploded. Others report fire and smoke. I can see no fire or smoke from here, but my view is to the west.