Police say they can't rule out Loyalist paramilitary involvement in eight racist attacks across homes in east Belfast.
23 police officers and an MP were among those injured during a night of fierce violence in Northern Ireland.
Twenty-nine police officers were injured during sectarian riots between republicans and loyalists in east Belfast today.
Sir Richard Branson's airline Virgin Atlantic is set to fly from Northern Ireland for the first time.
A total of eight services will be opened between Belfast and Orlando in Florida in June and July 2015.
Virgin is also expanding its existing Las Vegas services by operating flights to the Nevada gambling city from Glasgow in autumn 2015.
Twelfth of July parades in Belfast have passed off peacefully, according to UTV reporter Marc Mallett.
Three men were stabbed in the early hours of Saturday morning in sectarian clashes ahead of the parades.
Three people have been stabbed in Belfast as the city prepares for annual Twelfth of July celebrations.
Bonfires are traditionally lit in Northern Ireland on the Eleventh Night, but the occasion this year coincided with sectarian conflict and fighting.
In one case a gang of around 40 republicans and loyalists had to be separated by police.
The three victims, aged 28, 21 and 19, were injured in separate attacks in the early hours of Saturday morning.
Eight people have been arrested for public order offences in north and west Belfast overnight. Trouble flared during the Eleventh Night, an annual marching season celebration involving the lighting of bonfires.
Police Service of Northern Ireland (PSNI) assistant chief constable Will Kerr said:
I am pleased that last night was one of the most peaceful in recent years and am encouraged by the responsible behaviour of the vast majority of people involved.
I appreciate the efforts of all those involved in ensuring this was the case and I would continue to encourage everyone to work together to ensure that today passes off peacefully and that local communities are not disrupted with the violence witnessed in previous years.
A man has been stabbed during fighting between republican and loyalist factions in Northern Ireland ahead of the annual 'Twelfth of July' commemorations.
The victim, 28, was treated in hospital for injuries which are not believed to be life-threatening, police said.
A Police Service of Northern Ireland (PSNI) spokesman said: "At approximately 3.10am, police received a report that a man had been stabbed and that rival factions were fighting in the area [...] Police attended the area and the two groups were separated at approximately 3.30am."
The violence happened at the Ormeau bridge, an arterial link which separates predominantly nationalist and unionist residential areas.
Orange Order marches through northern Belfast have thus far gone by peacefully, UTV's Marc Mallet reports.
Orangemen and women have been urged to post "selfies" on the biggest day of the Protestant marching calendar.
Large crowd if supporters singing the sash and cheering the Ligoniel Band as it passes Twaddell protest camp http://t.co/4PF1lL2fMt
Minimal police presence at shop fronts. No resident protest groups http://t.co/BMljYS1Kcy
Orange March past Ardoyne shop fronts has passed peacefully. Roads now reopened
Police and Orangemen have expressed hopes violence will be averted in Northern Ireland today as protests are expected against a restriction on the "Glorious 12th" marches in Belfast.
The annual parade marks the Battle of the Boyne, the Protestant victory over Catholic troops in 1690.
But up to 50 protests are planned this evening in anger at the Parades Commission decision to prevent Orange lodge members walking along a section of the Crumlin Road next to the nationalist Ardoyne neighbourhood.
Grand Lodge of Ireland Grand Secretary Drew Nelson said every effort had been made to deliver a peaceful day.
"I would have a message for young protestants or any protestant or unionist who feels strongly about what's happening now - if you lift a stone or a bottle on the Twelfth day you are falling into a republican trap," he said.
Police have confirmed dissident republican Tommy Crossan was shot several times while he sat in an office yesterday.
The 43-year-old father-of-six, who was a former senior member of the Continuity IRA (CIRA).
Crossan, who also had five grandchildren, was gunned down at a fuel depot in the grounds of an industrial complex in full view of surrounding houses yesterday afternoon.
Police also wanted information about a red BMW, registration OEZ 9177, which is believed to be linked to the murder. It was found burned out a short time later in the Beechmount Grove area of Belfast, he said.
Deputy First Minister Martin McGuinness condemned the fatal shooting of Tommy Crossan, saying:
The people behind this killing are criminals and will further no cause through this shooting. Whoever carried out this act has nothing to offer the community and have no role to play in our future.
Dialogue not destruction is the way forward and while there may be a small minority of people who are trying to promote division and heighten tensions, let's be very clear, they will fail.The peace process is rock solid and all right thinking people across the community oppose and reject the actions of the people behind this murder.