Twenty-six police officers have been injured while protecting contractors removing bonfire material in west Belfast.
Large groups of youths threw petrol bombs, masonry and other missiles at officers in Distillery Street, a PSNI spokesperson said.
Police were there in support of contractors tasked by the landowner to remove bonfire material.
Chief Constable Simon Byrne said his officers had faced “shocking violence”.
‘Sick of being a punchbag’
Supt Melanie Jones said “at least 26 officers have sustained injuries and are currently receiving treatment”.
“Footage from evidence-gathering cameras will be reviewed and all efforts will be made to identify those involved,” she added.
“People who choose to engage in criminal and anti-social behaviour must understand it is unacceptable and must stop.
“Parents and guardians have an important obligation to keep young people safe by knowing where they are going and who they are with.”
Bonfires are lit in some republican areas in early August to mark the anniversary of the introduction of internment – or detention without trial – on 9 August 1971.
Mark Lindsay, chair of the Police Federation for Northern Ireland, said officers were “sick of being a punchbag for a society that has failed to tackle contentious issues”.
“The attacks were pre-meditated,” he said. “Petrol bombs and chunks of masonry don’t materialise out of thin air.
“What happened posed real risks to the lives of officers. Petrol bombing is a clear attempt to murder or maim officers who were there to uphold the law”.
Chief Constable Simon Byrne tweeted: “My thoughts are with our injured colleagues who faced shocking violence just trying to do their job.”
Alliance Policing Board member John Blair said such behaviour was “utterly unacceptable” and he hoped the injured officers make a full recovery.
“The people of the area have been quite clear they do not want these bonfires,” he said.
“I offer the residents my support in their desire to live in peace, and I hope the police are able to review footage to find those responsible.
“I urge anyone with information on this attack to contact police with it immediately.”