The North's Chief Constable, Hugh Orde, has appealed for calm on the streets of Belfast ahead of the 12 July Orange Order parades.
Unionist politicians have also appealed for calm following two gun attacks in north Belfast early this morning.
Loyalist paramilitaries are being blamed for the incidents in which one man was shot dead and another was critically wounded.
Detective Chief Superintendant Phil Wright said it is believed the two incidents are linked and may be part of the continuing tension between loyalist paramilitaries.
A 19-year-old was fatally wounded by three gunmen who burst into a house at Dhu Varren Crescent in the north of the city.
A light blue Peugeot car suspected of being used by the killers was found on fire soon afterwards at Cupar Way in the loyalist Shankill area.
In a separate attack earlier, a man in his 20s was shot several times at Crumlin Road, near Glenbank. Police said he was critically wounded.
