Flash mob of teens shuts down Tinley Park carnival.

Tinley Park canceled the final day of its Armed Forces Weekend Carnival after a "flash mob" of 400 teenagers showed up at the weekend festival and started fights. Police said that "another flash mob" was being promoted on social media for Sunday, and the event was canceled over "safety concerns." A police officer was injured trying to break up a fight and was treated at South Suburban Hospital Saturday evening, police said. Five teens were issued citations for fighting in public.