Authorities arrested three protesters during a third straight night of unrest in Ferguson, Missouri.

The heightened tension comes amid speculation that an announcement could come soon about whether to indict Ferguson police Officer Darren Wilson in the Aug. 9 shooting death of Michael Brown.

St. Louis County police say large groups of protesters blocked traffic three times in the St. Louis suburb Friday night. That happened twice near the police station and once on West Florissant Avenue, the site of violent protests soon after Brown's death. A motorist lost control and crashed into a light pole during the unrest on West Florissant.

Prosecutors said around noon on Friday that the grand jury was still in session. Brown's family, police and activists have called for calm.

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