Missouri Gov. Jay Nixon has declared a state of emergency and activated the National Guard in advance of a grand jury decision about whether a white police officer will be charged in the fatal shooting of a black 18-year-old in the St. Louis suburb of Ferguson.

Nixon said Monday that the National Guard would assist state and local police as needed, in case there is civil unrest when the grand jury’s decision is announced.

There was no indication an announcement is imminent. There is no specific date for a decision to be revealed about whether Ferguson Police Officer Darren Wilson should face charges for shooting Michael Brown on Aug. 9. The St. Louis County prosecutor has that he expects the grand jury to reach a decision in mid-to-late November.

(AP)