Pakistan’s government has launched a crackdown and arrested several protesters of former prime minister Imran Khan’s party that started a sit-in in Islamabad to demand his release from jail, according to the opposition political party.

Thousands of security forces poured into central Islamabad in an attempt to quell protests in support of Khan that have gripped the capital.

The demonstrators want the federal government to resign over what they call rigged general elections this year.