Professor Jacobson over at Legal Insurrection points out that just as at Newtown, nearly all the reporting done immediately after the bombs went off in Boston was wrong.  

As one commenter put it:

  "I am a retired airline pilot, and whenever there was some sort of aviation incident, people would come up and ask what happened. My standard reply was that in the first 24-36 hours, you could have reasonable confidence that something happened, where it happened, and with much less confidence the number of fatalities. Otherwise, just ignore the reports. These days, I apply that to most any disaster. It works well."

Indeed.  It takes at least a day or two before all the initial inaccuracies are corrected, and the real scope of things becomes clearer.  Fold in media bias, and it might take weeks to finally figure out what really happens in any disaster/crime story.