There are almost 300 million Americans. There are about as many guns there as people. Considering that, these shootings are pretty rare, even if it's a tragedy every time it happens.
Wanna have Swedish or British gun laws in the US too? Only the criminals armed? I talked with a girl on a Swedish site before. She told me that her taser, that she has to have illegally due to our gun laws, has saved her from being raped once.