Researchers in Washington State studied the lives of people who were admitted to hospitals with firearm injuries. From the Seattle Times:

The study highlighted a strong correlation between firearm-related hospitalizations and poor outcomes after being discharged, including repeated hospitalization, commission of crime and death. A quarter of those hospitalized for a firearm-related injury were arrested for firearm-related crime within the next five years.

Researchers found that those hospitalized with a gun-related injury who had a prior arrest for gun-related or violent crime were 43 times more likely to be slain within the next five years than those without either.

You can read this whole article and not find a clear reference to “gangs.”