MONTREAL—Business owners in Old Montreal will be assessing the damage this morning after an anti−curfew protest turned violent. Hundreds gathered in defiance of an 8 p.m. curfew that took effect in Montreal and Laval Sunday night. The mostly young crowd danced to music from loudspeakers while lighting fireworks and chanting, “freedom for the young.” However, the festive atmosphere quickly soured as a few protesters lit a garbage fire in Montreal’s Jacques Cartier Square. Police fired tear gas and rushed the crowd, prompting dozens of protesters to scatter and cause mayhem down the cobblestone streets of Montreal’s historic tourist district. Some protesters lit garbage fires at many intersections and seized projectiles from city streets, hurling them at nearby windows and shattering many. A police spokeswoman said seven arrests were made, though there was no immediate word on charges, and that 107 tickets were issued for public health infractions. The spokeswoman said …