At least 29 police officers have been injured in Northern Ireland as they tried to separate groups of pro-British loyalists and rival Irish nationalists.
The violence followed another protest by the loyalists against a decision to restrict the number of days the Union flag is flown over Belfast City Hall.
The latest rioting happened when loyalists returning from a demonstration in Belfast city centre, walked passed an area where nationalists live.
The BBC reports the nationalists attacked the loyalists with stones and there was some hand-to-hand fighting.
Police separated the two groups and fired several non-lethal plastic bullets.
Loyalists then turned on the police and threw stones and fireworks at them.
Politicians are trying to stop the violence but the demonstrators say they will keep on protesting.