These community organizers have helped stop daily gun violence. Can their lessons prevent mass shootings?

Community violence prevention workers have established a track record of successfully intervening in retaliatory gun violence

For decades, US researchers have studied behavioral signs that could help identify people who are at risk of carrying out mass violence.

They have looked at histories of drug abuse, interpersonal violence or red flag behaviors" like posting images of firearms on social media and threatening their classmates or co-workers.