Police in Northern Ireland arrested a 38-year-old man on suspicion of attempted murder on Saturday after reports that shots were fired at officers during fresh rioting in Belfast.
Police deployed water cannon and fired baton rounds in the third consecutive night of violence in the east of the city, facing off against more than 100 people throwing fireworks, bricks and other masonry, a spokesperson said.
The rioting followed a largely peaceful demonstration by more than 1000 people outside Belfast city hall against the city council's decision last month to limit the days it flies the British flag each year.
The December 3 ruling was viewed by pro-British groups as a concession too far to republicans who want Northern Ireland to be part of Ireland and sparked weeks of street violence.
Several people were arrested for public order offences during Saturday's disturbances, police said, and at least one officer was injured.
"Police are also investigating reports that a number of shots have been fired at police lines on the Newtownards road (in traditionally pro-British east Belfast)," a spokesperson said.
"A 38-year-old man has been arrested on suspicion of attempted murder."
Thirteen people were charged with public order offences on Saturday, one of them in relation to that day's rioting, during which at least one police officer was injured, according to the spokesperson.
The other 12 people were charged over disorder on Friday night, when up to 300 people hurled petrol bombs, fireworks, ball bearings and masonry at police, leaving nine officers injured.
On Thursday night, about 100 people were involved in the violence, which police and politicians have blamed on loyalist paramilitaries.
Conall McDevitt, a member of the Northern Ireland assembly for the republican SDLP, said the apparent use of guns in Saturday's unrest undermined the demonstrators' claim to be involved in legitimate protests.
"Whatever grievance some people may have had, it is totally lost when they allow people to use these protests as cover for attempted murder," he said.
"There is only one response possible, and that's a firm policing response against everyone involved in illegal protests and anyone seeking to organise or encourage illegal or violent demonstrations," he added.
On Friday, First Minister Peter Robinson, the leader of the Protestant, pro-British Democratic Unionist Party (DUP), said attacks on police officers were a "disgrace, criminally wrong and cannot be justified".
The December flag vote has raised tensions in the province, which endured three decades of sectarian violence until 1998 peace accords led to a power-sharing government between Protestants and Catholics.