CHIEF Constable George Hamilton has blamed the group known as the ‘IRA’ for being behind recent gun and bomb attacks on police in Derry.
Four explosive devices and six shots have been fired at police during almost a week of trouble in the city.
Police say two improvised explosive devices and 74 petrol bombs were hurled at officers during a sixth night of continuous violence overnight on Thursday.
The chief constable said that while several groups were involved in the trouble, the ‘IRA’ - sometimes referred to as the New IRA - was responsible for the attacks on police.
"We believe there are members of a variety of dissident groups in this disorder - the so-called New IRA is the main group behind these murderous attacks on police,” he said.
"We want to police with the community and protect people, we're working hard to maintain protecting people, locking up those responsible and bringing them before courts.”
He warned that someone could be killed.
"My fear is someone will be killed or seriously injured, we've already had police officers injured this week," he said.
"It's only a matter of time before a police officer or a child is injured or worse."
Police also said officers fired four plastic bullets. A picture circulating on social media yesterday appeared to show injuries caused to a youth after he was struck by a plastic bullet.
Earlier this week six shots were fired at police while two pipe bombs were also thrown onto the city's historic walls.
Searches were carried out around the Bogside yesterday believed to involve members of the the British army’s bomb squad.
During a press conference yesterday Mr Hamilton defended the PSNI operation in Derry.
"We don't want to be fighting with anyone, we use balanced judgment when to go in and when to stay out and operational decisions are made on a routine basis," he said.
"I'm not saying we always get it right but we certainly won't condone unlawfulness, we will pursue those who break the law and bring them before the courts."
He also defended the use of plastic bullets, which have killed people in the past.
"There's a long history of use of baton rounds in this jurisdiction and it is much safer now than previously," he said.
"We don't want to use these against communities, we have to act in a proportionate manner, but we need full range of tactical options available to us."
Police last night said a 50-year-old man is due before Omagh Magistrates' Court today charged with disorderly behaviour. He was arrested in Derry in the early hours of Friday morning.
Last night hundreds of people from across Derry turned out at a rally to protest against the six nights of violence in the Bogside area of the city.
Residents, clergy members including Bishop of Derry Donal McKeown, and politicians from across the divide turned out at Butcher Gate, the spot where police Land Rovers were attacked with petrol bombs on Thursday night.
Mayor of Derry John Boyle, SDLP leader Colm Eastwood, civil rights activist Eamonn McCann and Sinn Féin's Mary Lou McDonald were all in attendance to stand in defiance of what they say is dissident republican influence exploiting vulnerable teenagers in the area.
Fiachra McGuinness, son of the late former Stormont deputy first minister Martin, also attended in support of his father's former neighbourhood.
Bishop McKeown told the rally: "This city has learned that violence and destruction doesn't benefit anyone. Talking is the only thing that will build up community.
"You can't claim to love your country and cause destruction and pain to those who live in it. All who live here deserve to be cherished equally. We all want a city that everyone feels they have a future, because we have all lost too many people.
"Nothing can be built with petrol bombs and stones thrown in anger. The people of Derry deserve so much better than violence."
There was also condemnation of recent disorder in the city from secretary of state Karen Bradley, who said the trouble "was completely unacceptable".
"These sustained attacks have been widely condemned and must end," she said.
Police Federation spokesman Mark Lindsay also condemned the violence, while the Joint Committee on the Implementation of the Good Friday Agreement said: "We wish to express our deep concern and alarm at reports of violence in the north over recent days, particularly in parts of Belfast and Derry".
Sinn Féin president Mary-Lou McDonald said: "We need to send a strong message to those responsible that they do not act in our name. That they will not succeed".