The massacre at Virginia Tech University has renewed widespread debate about gun control laws in the United States.
Advocates for tighter measures say gun violence would decrease if weapons were not as accessible. But others argue that if guns were more readily available, a licensed gun owner could shoot or disarm an attacker.
The Federal Bureau of Investigation oversees a system of background checks on potential gun buyers. Checks are conducted by the FBI, state or local agencies. The FBI says more than 50 million background checks have been performed. The FBI adds that, as of late 2005, almost 500,000 people were prevented from purchasing firearms.
Australia's Prime Minister John Howard pushed through tough gun laws in the wake of a shooting rampage in his country in 1996.
School shootings are not solely a U.S. phenomenon. A global organization that monitors gun violence, the International Action Network on Small Arms says students or former students have gone on shooting rampages at their schools in Sweden, Argentina, Germany and elsewhere.
Some information for this report was provided by AFP, AP and Reuters.