The first attack happened around 8:25 p.m. Saturday when a man was attacked after parking his motor scooter near the Northwestern University campus in Streeterville. The man had parked on the 300 block of East Chicago Avenue across the street from Wieboldt Hall when a group of 15 to 20 men, all approximately 16 to 20 years old and black, approached him, according to an alert from the university. One of them threw a baseball at the victim’s face and knocked him to the ground, the alert said. Several others from the group punched and hit him several times. The...