By Sunday afternoon clashes were continuing between police in riot gear and a few hundred protesters. Many protesters had come armed with batons and slingshots.
Shipping containers were set ablaze, several vehicles stood torched, and hundreds of tear gas canisters lay strewn on the ground on Islamabad's normally pristine Constitution Avenue following more than 15 hours of battle.
Nearby, a group of up to 15 teenage protesters armed with bamboo clubs and rocks attacked a vehicle carrying three United Nations staff members.
"Their vehicle was damaged but they escaped unhurt," a UN source told AFP.