A speeding maroon Mitsubishi SUV raced the wrong way up Commonwealth Avenue from Kenmore Square early Thursday afternoon, sideswiping at least eight cars and colliding with two more before the driver stopped and fled on foot. Marouk Onifade, one of those whose car was sideswiped, chased down the suspect and held him until police arrived to take him into custody. “I didn’t hold him long,” says Onifade, a native of Benin, West Africa, who works in real estate in Boston. “The police were already very nearby.” Onifade downplayed assertions that his actions were heroic. Boston Police were called at...