Several hundred loyalist rioters launched vicious attacks on police on a night of shame in Belfast city centre.
t least 26 officers were injured – a number were hospitalised – and a number of arrests were made when loyalists demonstrating against a republican rally rained missiles down on police lines during a sustained onslaught in the heart of the city.
Mobs pelted police with bricks, bottles and metal grates on Royal Avenue which forced the re-routing of the parade.
Around 20 baton rounds were fired by police and water cannon deployed as officers battled to quell the trouble.
An anti-internment rally had been due to make its way from Ardoyne to Andersonstown, with part of the route taking marchers along Royal Avenue and Castle Street.
But due to the violence it was re-routed along Carrick Hill.
A city centre bar was attacked and bins, glasses and bottles removed and used by loyalists against the police. Parked cars were also set on fire during the disturbances.
Among frightened bystanders were visitors to Northern Ireland for the World Police and Fire Games.
Last night's shocking scenes came in the same week the country was widely-praised for hosting "the friendliest games in history".
East Belfast Ulster Unionist MLA Michael Copeland alleged he, his daughter and wife were struck by police and said he would be making a formal complaint.
Assistant Chief Constable George Hamilton described the police's overall response to the violence as "proportionate".
"Whilst facilitating the Parades Commission determination for tonight's parade and associated protests, police have come under heavy and sustained attack by crowds intent on creating disorder," he said last night.
"As Northern Ireland moves ahead, the effect of tonight's violence has the potential to damage the local economy and the reputation of Belfast as a tourist destination.
"As disturbances are continuing, I would call upon people of influence in communities and those in political leadership to do all possible to reduce tension."
A huge police presence was in place in Royal Avenue at its junction with North Street after 5pm.
The Parades Commission had been notified of six protests, totalling around 600 unionists. Last night that number was a fraction of those who took to the streets.
By 6pm a huge crowd of loyalists gathered on the road at the junction, blocking the route of the anti-internment parade.
Within minutes simmering tensions exploded into violence, police coming under sustained ferocious attack with bottles, bricks, golf balls and marbles thrown.
Within minutes a water cannon was brought to the front line with police faced with huge bodies of protesters on both Royal Avenue and North Street.
An object struck one police officer so hard he was immobile for around 30 minutes as paramedics tending to him.
As the intensity of the attacks increased, police resorted to the use of plastic baton rounds.
Police reinforcements were brought in, including dog handlers, and both sets of protesters were eventually driven away from the junction.
The march, which started in north Belfast, marked the introduction of internment in 1971 and what the organisers said was ongoing internment by remand.
It was held by police for a time at North Queen Street. The organisers had notified the parading watchdog of thousands of participants but that number was in the hundreds last night.
It eventually made its way along Carrick Hill shortly past 9pm after protesters had been pushed back to the Shankill Road area.
There were reports of members of the parade throwing stones at loyalist protesters as they passed.
North Belfast DUP MLA Nelson McCausland described it as "a bad night for Belfast".
"What should have been a great week for the city, with thousands of visitors for the World Police and Fire Games, has ended badly and the image of Northern Ireland has been tarnished by violence," he said.
A business owner in the city centre said his property had been targeted by loyalists as they armed themselves with more objects to use against police.
The trouble in Belfast has broken out at an unfortunate time for tourist chiefs and civic leaders as the city is currently hosting thousands of international visitors for the World Police and Fire Games.