There are reports on Twitter of an explosion at the Boston Marathon. We spoke to a Boston Police Department Spokesperson who said there was "some sort of incident at 671 Boylston Street", which is the finish line for the race. We will update as we know more. Boston marathon headquarters locked down after explosion reported near finish line: spokesman #breaking — Reuters US News (@ReutersUS) April 15, 2013 Two huge explosions just went off at #bostonmarathon finish.