BREAKING: TWO EXPLOSIONS AT BOSTON MARATHON: Updates from Ed Driscoll and Hot Air. Bloomberg TV currently has a live stream on the story.  CBS Boston has the initial video of the explosions.

UPDATE: First reports are always unreliable, but this looks pretty bad.

ANOTHER UPDATE: More from the Boston Herald, whose servers are groaning under the load. “It’s chaos down here. Two bombs just went off at the finish line within five seconds of each other. There must be casualties. Now I’m seeing fire trucks and ambulances racing down Boylston Street toward the scene.”

MORE: Photos, some appalling, at The Atlantic. (Bumped).