But in terms of casualties, this has to be the worse of all.
At least considering the injured many of those seem to have no serious injuries but rather "only" issues because of the tear gas.
Although there is also a number of people with gun shot wounds. I do not know the ratio though.
A heavily armed gunman clad in black kicked in an emergency door at a movie theater in Colorado early Friday, hurled two canisters of an unknown gas and opened fire on the stunned audience, killing at least 12 people and wounding dozens of others who were watching the midnight premiere of a new Batman film. Law enforcement authorities identified the alleged gunman as James Holmes, 24, and said he was taken into custody in a parking lot behind the theater after the attack.
Holmes was a graduate student in neuroscience at the University of Colorado-Denver’s Aschutz Medical Campus, officials there said, but was in the process of withdrawing from the program. - Washington Post
Sadly, the "evil fame" is what drives those nutters. The best punishment would be locking him up/shooting him - whatever - but not giving him any media time. Not showing the face, the name etc. I know it's pretty much impossible in times of blogs and facebook, and the public demands a face. But it's a reward for those guys.