Armored vehicles lined this battered city’s main thoroughfares and thousands of law enforcement officers and National Guard troops worked to maintain order and enforce a citywide curfew Tuesday night, amid scattered reports of unrest after a day of largely peaceful protests. As the curfew went into effect at 10 p.m., hundreds of people remained in the streets near the intersection of Pennsylvania and West North Avenues in blighted West Baltimore, where a CVS drugstore had been looted and burned...