Read there are more than 20,000 (or 300 depending on the source, still a lot) gun-related laws on the books, one new gun law or twenty new gun laws would not have prevented this tragedy. Further restricting the millions of law-abiding gun owners doesn't "fix" the problem and is not the answer. The evidence shows restrictive gun laws or lax gun laws are a minor contributor compared with the socio-economic factors predicating murder however violent crime rates are reduced where law-abiding citizens are armed.

Quoted from another site comparing violent crime in various California cities:

The desire to reduce murder is both understandable and laudable. The desire to find one simple cause, which can then be eliminated, is also understandable, though clearly absurd. But the evidence shows that lax gun laws alone are not a major factor -- and the range of murder rates in California suggests that the major factors are many, many times more powerful than lax gun laws.
It is a fact that even complete bans on firearms do not prevent gun-related violence and in many cases result in a greater incidence of violent crime due the reduced deterrent.

The facts are out there, we need to make sure our law makers know them as well.