At this point it seems Cambridge and Boston in general is shut down and locked down.  The universities and schools across Boston are closed.  People are literally being kept off the streets.  Incredible.

Pete Williams is reporting that they are brothers, 19 and 20.  The one at large is Cambridge resident.  Tsarnaez is the name being identified.  No nationality given, but repeated that they've been in the U.S. for a year or so.  The one at large is 19.

Less emphasis on the idea that police suspect they know where he is.  A lot of public transit is shut.  NBC estimates 320,000 in the area around Watertown are being told to stay home.