Students have started protesting poor conditions in public schools, such as lack of insulation causing horrible cold and heat, presence of rats, etc. When the kids started protesting they were attacked by cops. Things like rubber bullets knocking out teeth and breaking bones and stun grenades causing burns and even blowing off a teen's hand.

The cops are also allegedly ranting about how they're looking forward to putting the kids in their place, as pigs are wont to do.

Naturally, reasonable people (particularly parents) don't like when kids are being maimed for peacefully protesting. This led to adultsjoining the protest to protect kids and the police kept escalating until the whole thing turned into a riot.