A 16-year-old boy was killed and a 40-year-old man badly hurt Friday morning during a drive-by shooting in the Brighton Park neighborhood on the Southwest Side. They were in the street in the 2500 block of West 46th Street when an assailant inside a sport-utility vehicle opened fire about 10:40 a.m., hitting the boy in the head and chest. The unidentified boy was taken to Mount Sinai Hospital where he was pronounced dead and the man, shot in the leg and chest, was in "grave" condition, police said. No arrests have been made. Area One detectives are investigating.