( CNN ) -- Police were watching for any further violence Wednesday after a third night of rioting in Belfast , Northern Ireland , that left one officer hurt , officials said . About 150 nationalist youths fired shots and threw petrol bombs and a pipe bomb at officers . They also shone high-powered laser pens into officers ' eyes . The Police Service of Northern Ireland said it was now investigating and hoping to identify those involved in Tuesday night 's violence . Burning barricades were set up in the Ardoyne area of the city , which has been a flashpoint of the recent violence . One vehicle was hijacked and set on fire , police said . Police used water cannons to disperse the rioters and the violence was over by 2 a.m. ( 9 p.m . ET Tuesday ) , police said . One officer was hurt , but not seriously , police said . Earlier there were reports that several had been injured . Trouble also flared in other parts of Belfast . The latest violence began after a decision to allow a Protestant parade to pass through a mainly Catholic neighborhood on July 12 , a day when Protestants march to celebrate the victory of England 's King William III over his ousted Catholic predecessor , James II , in 1689 . Known as The Twelfth , the holiday has previously been marred by violence and has been a source of tension between Catholics and Protestants for years . Police had to remove demonstrators who staged a sit-down protest to block this year 's march . Rioting erupted a short time later and more than 50 officers were hurt . The previous night , 27 officers were hurt , including three who were shot at close range by a masked man armed with a shotgun . Speaking at the House of Commons on Wednesday , British Prime Minister David Cameron condemned the `` completely unacceptable behavior '' of the protesters and praised the police as `` brave '' and `` restrained . '' `` Over 80 police officers have been injured after being attacked , including by petrol bombs , pipe bombs , and bricks , '' Cameron said . `` The police came under fire on Sunday night , and shots were again fired last night . The police have been forced to retaliate with baton rounds and with water cannons . '' Cameron said Northern Ireland 's police force is under local control , no longer governed by London , so `` there is no excuse for anyone not to cooperate with that police force . '' Journalist Peter Taggart in Belfast , Northern Ireland , contributed to this report .
NEW : One officer was hurt in a third night of violence in Belfast . NEW : About 150 youths fired shots and threw bombs at officers . NEW : Police are now trying to identify those involved . BELFAST, Northern Ireland (CNN) -- Prime Minister David Cameron denounced `` unacceptable '' violence .