N Ireland leaders call for calm after violence escalates

Authorities in Northern Ireland sought to restore calm Thursday after Protestant and Catholic youths in Belfast hurled bricks, fireworks and gasoline bombs at police and each other. It was the worst mayhem in a week of street violence in the region, where Britain’s exit from the European Union has unsettled an uneasy political balance.

Crowds including children as young as 12 or 13 clashed across a concrete “peace wall” in west Belfast that separates a British loyalist Protestant neighborhood from an Irish nationalist Catholic area. Police fired rubber bullets at...