FERGUSON, Mo. (AP) — The FBI is investigating possible civil rights violations after a suburban St. Louis police officer fatally shot an unarmed teenager.

Cheryl Mimura, a spokeswoman for the FBI’s St. Louis field office, says the agency opened an investigation Monday into possible civil rights violations arising from the death of 18-year-old Michael Brown. Police say Brown was shot multiple times Saturday in a scuffle with an officer in Ferguson.

Mimura says the FBI is monitoring the case and working with St. Louis County police.

A candlelight vigil for Brown was held Sunday, and tensions erupted later that night. Nearly three dozen people were arrested after a crowd looted and burned stores, vandalized vehicles and taunted officers.

Mimura noted that the FBI would be investigating such a shooting regardless of the public attention.

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