A banned Islamist group prepared to march on Pakistan’s capital Islamabad on Thursday even as authorities vowed to hold them back with force after deadly clashes the previous day.

Thousands of members of the banned Tehrik-e-Labaik Pakistan (TLP) group had been gathered since Friday on a highway, just outside the eastern city of Lahore, with a series of demands including the release of their imprisoned leader. On Wednesday they began marching north towards Pakistan’s capital.

“We have started marching towards Islamabad, police have barricaded the road, but we will remove them,” a TLP spokesman told Reuters.

Clashes on Wednesday evening killed around four police officers and several TLP members, and wounded dozens. The country’s information minister had said they would be treated with full force as a militant group and not allowed to enter the capital, where shipping containers had been set up to block roads.

“Police from three districts have been called while Rangers are on the alert,” a senior police official told Reuters requesting anonymity, referring to paramilitary troops that the government had called on to help contain the protesters, who were blocking Pakistan’s busiest highway.

A government team was negotiating on with the TLP, with talks led by its chief, Saad Rizvi, from a prison in Lahore, two government sources told Reuters.

A provincial Punjab government spokesman did not immediately respond to request for comment.

The talks were confirmed by the TLP.

“The government initiated another round of talks with TLP ... Saad Rizvi and two other leaders are participating in talks with the TLP side,” a TLP spokesman said.

Besides demanding the release of their leader, the TLP activists have been calling for the expulsion of France’s ambassador over the publication of a series of caricatures by the French satirical magazine Charlie Hebdo.

It is the group’s third countrywide protest campaign since 2017 over caricatures that are considered deeply insulting by Muslims.