Gun ownership - reduce or increase incidents?

I was wondering how effective the gun policy is in the U.S. or other countries that legalize gun ownership. I think it contributed to the recent Virginia Tech incident.

The policy of legal gun ownership and control has perhaps been debated since the birth of the gun itself.

There are two arguments - for and against legal gun ownership. One argues that we need guns to protect ourselves against criminals, or that gun ownership is part of constitutional rights. One can also argue that if guns are banned, we need not to worry about having guns.

One argument for legal gun ownership is that it saves lives. It sounds ridiculous, but that's what statistics tell, says National Center of Policy Analysis, a U.S. non-profit organization.

I think the statistics showcase more on the illegal ownership of guns. How many incidents have been related to legally-owned weapons? Not as many as the illegal ones, I presume. Those that are well-known include Columbine until the recent Virginia Tech incidents. And another incident yesterday at NASA's Johnson Space Center.

How about in countries where gun ownership is not (publicly?) legal? Like in Indonesia with Tommy Suharto and Adiguna Sutowo, for example. Or like in Malaysia with the murder of a Mongolian model. All three involved guns and related to elite or politicians.

It's logical to assume that these shooting incidents will increase if gun ownership is legalized.

With the speed the world is going today, there will be stressed people and lunatics out there. A lot of them. Don't equip them with guns. Gun ownership should be made illegal.

Update:
- Mass shootings more common since 1960s.
- Ria Wibisono has concern over similar bullying practice (and racism) in Indonesia, which she expressed on Overseas Think Tank for Indonesia.