The Crime Prevention Research Center does amazing work that is widely considered to be not only accurate, but undisputed.
In this article, they present the FACTS on mass shootings and the relationship they have to so-called Gun Free Zones.
The original title of this article was ... "More misleading information from Bloomberg's Everytown for Gun Safety on guns: 'Analysis of Recent Mass Shootings,' Showing how mass public shootings keep occurring in gun-free zones" It was originally posted on September 9, 2014.
While the first part of the discussion here goes through each mass public shooting from 2009 to 2014 discussed in the Bloomberg report. At the end of the post, we have a response to Everytown's response to our post.
We have since updated our information up through May 30, 2018.
An Excel spreadsheet that lists all the mass public shootings from 1998 through April 30, 2018 is available here: Case by case discussion of which cases have been in gun-free zones. Broader information on these shootings is available here.
The report by John Lott and Bill Landes on gun-free zones that covers earlier years from 1977 to 1999 is available here (the raw data used in this study is available in a STATA file, though the sums by state and year). We used the cases identified by the New York Times that are discussed in Lott and Landes for years prior to 1977 (though the web version doesn't have the chart that lists out each case). A case by case discussion on the New York Times cases can be found at the bottom of the article.
~ I am not the author of this article, and give full attribution to The Crime Prevention Research Center, its authors, contributers, and its affiliates.