Some idiot on another website blamed it on President Obama. People will turn any tragedy into an excuse to spew their political beliefs. Tragedies seem to bring the trolls out in full force.
The person who committed the crime is the one responsible. However, some will try to place blame on everything under the sun to gain sympathy for the killer. I expect to here in the next few days about his horrible childhood, mental health problems, school stress, and how he couldn't find a girlfriend.