CHICAGO (WLS) -- A man was critically injured in a drive-by shooting on Chicago's Northwest Side Monday afternoon.Police said a 30-year-old man was sitting in his vehicle in the 5300-block of West Oakdale when another vehicle pulled up alongside him and began firing.The victim suffered a gunshot wound to the head and was rushed to Illinois Masonic Hospital in critical condition, police said.No one is in custody. Area North detectives are investigating.