Wikipedia has a list of school rampage murders world wide... It is not just a United States problem.
The Anarchist Soccer Mom: It is time to talk about mental illness. And TOM links to an Althouse post that notes there were less of these sorts of attacks when committing someone was easier.
While access to guns (to the perpetrators) combined with restricting weapons to law abiding persons makes these attacks easier to pull off, the driving force that motivates these events is attention. The media and public attention post attack makes the next attack far more likely.
Morgan Freeman did not make this statement, but frankly it makes so much sense he should have claimed it. It is the sensational media that spurs these attacks, not the access to guns.
Violent crime is much higher in countries with strict gun control (imagine that?)
Obama promises to use all his powers to change the Second Amendment
h/t to DrewM at AoSHQ for the ASM article.