This says it best.....
"So three of the gunmen in the newspaper’s four prominent examples complied with gun control, and it failed to stop them. One of the gunmen–Adam Lanza–chose not to comply, and gun control actually aided him by leaving Sandy Hook Elementary teachers and students in a defenseless position in a gun-free zone."
And the common theme in all theses cases is that is anyone of the victims was able to have a firearm or had a firearm they could have caused enough resistance in almost all of these cases that could have saved lives. I know if the Sandy Hook guy Lanza was confronted he would have folded and non of those children would have been hurt or killed.