Authorities said a police officer was shot Saturday night in Ferguson, Missouri, the scene of racial unrest in the wake of the August shooting death of a black 18-year-old by a white police officer.

Tim Zoll of the Ferguson Police Department told KSDK-TV that the officer was shot in the arm.

St. Louis County Police spokesman Brian Schellman told The Associated Press that an officer was shot but said he had 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 and spokesmen Saturday night were not immediately returned.

A county grand jury is weighing whether to indict Ferguson officer Darren Wilson in Brown's shooting.

The Justice Department, which is investigating whether Brown's civil rights were violated, is conducting a broader probe into Ferguson police. On Friday, it urged Jackson to ban his officers from wearing bracelets supporting Wilson while on duty and from covering up their name plates with black tape.

Ferguson residents complained about the bracelets, which are black with "I am Darren Wilson" in white lettering, at a meeting with federal officials this week.