Rioters in Belfast have thrown petrol bombs and other missiles at police, the BBC reports.
The riots coincided with the “Orange Parade”, an annual march of protestant unionists celebrating the 1609 battle victory of protestant William of Orange over Catholic King James II.
Dozens of police officers are reportedly injured from the riots. At one point a bus was hijacked and driven at the police.
This year has already been one of the most violent in Northern Ireland since the Good Friday agreement in 1998, according to CNN.
In The Guardian, Ireland correspondent Henry McDonald blames the rise in violence on political disillusion and the resentment of authority amongst Catholic youth, combined with the actions of rogue Loyalist and Republican paramilitary groups.