The trick CNN performs here is to use actual data from the CDC, but conflates both causes and sources of violence to create the appearance of a nationwide phenomenon.
Because "gun violence", so-called, is anything but national in scope or scale. It is in fact highly concentrated in a handful of urban areas, and is predominantly a result of gang activity and drug crime.
Another trick is to lump together all causes of intentional firearms deaths, including unintentional death, homicide, legal intervention, undetermined intent and homicide followed by suicide.
For example, if you look at the chart cited by CNN, you'll see the claimed number of "gun violence" deaths in 2012 is 33,563. But the CDC actually reports
11,208 deaths for that year due to "assault (homicide) by discharge of firearm".*
Furthermore, those deaths were highly concentrated in a handful of urban zones located largely within Baltimore, MD; Washington, DC; Detroit, MI; Chicago, IL; Houston, TX and Miami, FL. All of those areas have something in common - poor minority populations with high overall rates of gang-related crime, larceny, and drug abuse.
If you exclude such areas from the statistics representative of the rest of the country (i.e. - the vast majority of the United States), violence committed with firearms is not only rare, but exceptionally so given the high rate of gun ownership in the nation.
*Source:
http://www.cdc.gov/nchs/data/nvsr/nvsr64/nvsr64_02.pdf
