Pakistani security forces pushed a protester off a 25-foot tall stack of shipping containers as they were accused of opening fire on supporters of Imran Khan at a huge demonstration in Islamabad.

Thousands of supporters of Pakistan’s jailed former Prime Minister Imran Khan broke through barricades around the capital Tuesday and marched into Islamabad, clashing with security forces and demanding his release.

Pakistani authorities arrested nearly 1,000 supporters of jailed former prime minister Imran Khan who stormed the capital this week to demand his release, the city's police chief said on Wednesday.