At least six people have died in Pakistan after violence broke out during protests to free former prime minister Imran Khan, according to several media reports.

Supporters fighting for the release of Khan clashed with security services and broke through a ring of shipping containers locking down the capital Islamabad on Tuesday. According to Sky News, four members of Pakistan’s security services and one civilian were killed when a vehicle rammed them in a street.

No group has claimed responsibility for the attack. Another police officer died in a separate incident. Prime Minister Shehbaz Sharif said an “anarchist group” was deliberately targeting law enforcement.

In a statement, he said the unrest was aimed at achieving “evil political designs”, and added: “It is not a peaceful protest, it is extremism.”

Interior minister Mohsin Naqvi also threatened the use of live fire rounds if protesters used weapons shortly after midnight, saying: “If they again fire bullets, the bullet will be responded with the bullet.”

Several people have also been injured, including journalists who demonstrators attacked. The Associated Press said dozens of Khan supporters beat a videographer reporting on the protest for its coverage, and said its camera was taken.

It comes as the interior ministry said the army had been deployed to protect diplomatic missions in the fortified red zone area where many government buildings and embassies are located.