Virginia attack

I surfed to the site whose address iswww.slate.com. This site is talking about Virginia Tech syudent Cho Seung-Hui, especcially the guns that he used when he attacked. There is a question, 'How could he hace killed so many peolpe with just a couple of guns?'. They found the answer with his guns. And this site explains a lot of information about the guns.

When I saw this site is article, I was surprised; he killed 32 people during just 10~15minutes. I had a question: how could a person kill 32 people in such a short time, even if his guns were particularly powerful and dangerous?