ISLAMABAD (AFP) — Pakistani protesters demanding the release of ex-prime minister Imran Khan on Tuesday killed four members of the nation’s security forces, the government said, as the crowds closed in on the center of the capital.

Protesters armed with sticks and slingshots took on police in western Islamabad on Tuesday morning, less than 10 kilometers from the government enclave they aim to occupy.

Interior Minister Mohsin Naqvi said four members of the paramilitary rangers force had been killed in an attack by “miscreants” on a city highway leading towards the government sector.

Prime Minister Shehbaz Sharif said the men had been “run over by a vehicle.”

“These disruptive elements do not seek revolution but bloodshed,” he said in a statement. “This is not a peaceful protest, it is extremism.”

The government said Monday that one police officer had been killed and nine more were critically wounded in two days of clashes with demonstrators as they closed in on the capital.

‘Frustrated with government’

Khan was barred from standing in February elections that were marred by allegations of rigging, sidelined by dozens of legal cases that he claims were confected to prevent his comeback.

His Pakistan Tehreek-e-Insaf (PTI) party has defied a government crackdown with regular demonstrations aiming to seize public spaces in Islamabad and other large cities.

The capital has been locked down since late Saturday, with mobile internet sporadically cut and more than 20,000 police flooding the streets, many armed with riot shields and batons.

Last week, the Islamabad city administration announced a two-month ban on public gatherings.

But PTI convoys traveled from their power base in northwestern Khyber Pakhtunkhwa province and the most populous province of Punjab, hauling aside roadblocks of stacked shipping containers.

The government cited “security concerns” for the mobile internet outages, while Islamabad’s schools and universities were also ordered shut on Monday and Tuesday.

“Those who will come here will be arrested,” Interior Minister Naqvi told reporters late Monday at D-Chowk, the public square outside Islamabad’s government buildings that PTI aims to occupy.

PTI’s chief demand is the release of Khan, the 72-year-old charismatic former cricket star who served as premier from 2018 to 2022 and is the lodestar of their party.

They are also protesting alleged tampering in the February polls and a recent government-backed constitutional amendment giving it more power over the courts, where Khan is tangled in dozens of cases.