Violence has flared for the fourth night running in Northern Ireland, hours after politicians and Church leaders held talks in a bid to quell a row over the flying of the British flag at Belfast City Hall.
Northern Ireland's chief police officer Matt Baggott said on Sunday that 52 officers had been injured following three nights of rioting and attacks on police in the city.
Baggott warned that police would deal firmly with the violence for as long as it was necessary.
"You may be assured there will be sufficient resources in the event of more disorder for however long is necessary," Baggott said.
But as darkness fell on Sunday, a mob gathered and hurled steel barriers, bricks, fireworks and bottles at officers patrolling Castlereagh Street in the east of the city. Unrest was also reported on Mountpottinger Road and Beersbridge Road.
"What it quite clearly demonstrates is the fact that paramilitaries have hijacked this flags protest issue and they have now turned their guns on the police "
- Terry Spence, chairman of the Police Federation for Northern Ireland
The protests were triggered by a December 3 decision by the council to stop flying the British flag year-round.
The ruling was viewed by pro-British loyalist groups as a concession too far to Republicans who want Northern Ireland to be part of Ireland.
The discussions aimed at ending the violence took place at a Belfast church.
Robin Newton, of the Democratic Unionist Party, said a lack of engagement from protest organisers was making it difficult to see an end to the unrest.
"We have to find a way out of this, but how we do it I don't know," he said.
Police used water cannon and fired baton rounds on Saturday as they confronted more than 100 protesters who were throwing fireworks and bricks.
There have been on-off demonstrations in Belfast ever since the decision about the flag.
So far, 70 people have been arrested in connection with the sporadic rioting and 47 people have been charged with criminal offences.
Terry Spence, chairman of the Police Federation for Northern Ireland, which represents the interests of police officers, said the firing of shots at police proved that armed groups had infiltrated the protests.
"What it quite clearly demonstrates is the fact that paramilitaries have hijacked this flags protest issue and they have now turned their guns on the police," he said.
"There is no doubt that it has been exploited by the paramilitary grouping known as the Ulster Volunteer Force, and it is very clear that there are members of the UVF, leading members of the UVF, who are exploiting this and are organising and orchestrating this violence against police officers."
Northern Ireland endured three decades of sectarian violence until 1998 peace accords led to a power-sharing government between Protestants and Catholics.
Protestants mainly want to stay in the UK while many Catholics want to unite with the Republic of Ireland.