Northern Irish republicans threw petrol bombs at police and hijacked and burned vehicles after a major Protestant parade passed close to Catholic areas of the city of Londonderry on Saturday, according to Reuters. Seven people were arrested and charged with rioting and petrol bombing after the annual Apprentice Boys parade and a protest by republicans nearby. Pro-British Protestants march every summer to commemorate historical events, particularly notable British military victories, sometimes triggering a violent response from mainly-Catholic Irish republicans. Thousands watched the parade by some 10,000 Apprentice Boys on Saturday. Afterwards republicans threw petrol bombs at police and attacked armoured police vehicles. A woman and her daughter were dragged from their car when it was hijacked, a police spokeswoman said. Another car was burned elsewhere in the city and a post office van was seized and set alight by four masked men. There were no reports of injuries. British-controlled Northern Ireland has recently seen some of its worst violence since a 1998 peace agreement which ended 30 years of conflict that killed some 3,600 people. The agreement paved the way for a power-sharing government bringing together Protestant loyalists who want Northern Ireland to remain part of the United Kingdom, and Irish nationalists who want it to be part of a united Ireland.