Authorities say a police officer has been shot 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.

St. Louis County Police Chief Jon Belmar said that the officer approached two men around 9:10pm at a community centre, which was closed at the time. As the officer approached, the men ran away. When the officer gave chase, “one of the men turned and shot”, Belmar said.

The officer was shot in the arm and is expected to survive, he said. Belmar did not identify the officer or give further details about his condition. He said the officer returned fire but said police have “no indication” that either suspect was shot.

The shooting is not believed to be related to protests occurring elsewhere in Ferguson.

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The city has been the scene of unrest since the August 9 shooting of Michael Brown, an unarmed, black 18-year-old, by a white police officer.

The shooting on Saturday 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 on 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.