This week, an extended reminder.
As of October 8, at least 9,095 people had been killed by gunfire in the US since Newtown, at least 89 of them in Massachusetts.
FBI's definition of mass murder is the killing of four or more people
in a single incident with no distinctive time period between the
murders. By that definition, as of September 16, there had already been at least 17 mass murders with guns in the US this year.
A subreddit called "Guns Are Cool," which apparently doesn't actually
think so, came up with a definition of mass shooting as a case when four
or more people are shot in a spree, likely without a cooling off period
between shootings. It's much the same as the definition of mass murder
except no one need die. As of October 9, they had collected a list of 285 mass shootings in the US in 2013.