 At least 100 people were shot, 17 fatally, in Chicago over the Fourth of July holiday weekend. Locals say gangs are to blame, but they aren't the same as they used to be. Now they're running in smaller, more violent groups. One local neighborhood watch member saying a gang can be a block of people who don't like another block of people, adding that taunts on social media often lead to attacks. That's ABC's Allison Kosick in Chicago.