Violence erupted over the weekend in Roxbury and Dorchester, where three men were shot to death and another was wounded in separate attacks only hours apart.

Bernard Wheeler, 23, of Roxbury, was shot in the side at about 11:30 p.m. Saturday as he sat in a Hyundai Excel parked outside 68 Homestead St. in Roxbury, police said. He was pronounced dead at Boston City Hospital.