School / shopping mall / post office shooting.
So many of those mass killers were taking some selective serotonin reuptake inhibitors drug (SSRI) that it's almost impossible to find exceptions. If you are taking one of those drugs or know someone who is, then study the subject. Here is one of 30 thousand sites I found on my first search:
SSRI Stories http://www.ssristories.org/
SSRIs! It's not just mass murder, it's suicide too! Two side effects for the price of one!
Robin Williams' death highlights challenge of treating severe depression
CBS News | August 12, 2014
The U.S. Food and Drug Administration warns consumers that people who take SSRIs may have an increased risk for attempting suicide.
Shamed Glaxo's u-turn on 'suicide' drug
Daily Mail | 15 June 2004