FERGUSON, Mo. (AP) -- Authorities say a police officer has been shot in Ferguson, Missouri. Tim Zoll of the Ferguson Police Department tells KSDK-TV that the officer was shot in the arm. St. Louis County Police spokesman Brian Schellman tells The Associated Press that an officer was shot but says he has no further information. The circumstances surrounding the shooting were not immediately clear. The city has been the scene of unrest since the Aug. 9 shooting of Michael Brown, an unarmed, black 18-year-old, by a white police officer. The Saturday shooting comes after Ferguson Police Chief Tom Jackson issued a videotaped apology earlier in the week and attempted to march with protesters, an effort that led to a clash with activists and several arrests on Thursday. Messages left with Jackson Saturday night were not immediately returned.