Washington: Missouri Governor Jay Nixon has declared a state of emergency, anticipating unrest if a grand jury decides against indicting White police officer Darren Wilson in the fatal shooting of black teenager Michael Brown.
The St. Louis County grand jury that is probing the Aug 9 incident is expected to deliver its decision before the end of this month.
Brown's death triggered weeks of protests in the St. Louis suburb of Ferguson, a largely African American community with a nearly all-White police force.
The state of emergency, which remains in effect for 30 days, authorises the activation of the National Guard.
In his executive order Monday, Nixon instructed the State Highway Patrol, the St. Louis County Police Department and the St. Louis Metropolitan Police Department "to operate as a Unified Command to protect civil rights and ensure public safety in the city of Ferguson and the St. Louis region".
Nixon deployed National Guard units to Ferguson for several days in late August at the height of the disturbances sparked by the fatal shooting of 18-year-old Brown.
The Ferguson police department maintains that Wilson fired his gun in self-defence after Brown tried to grab his weapon. The dead youth's family and a number of witnesses say he had his hands in the air when the officer shot him.
Critics of the police are pessimistic about the prospects that Wilson will be indicted.
Don't Shoot, a coalition of more than 50 organisations, says it plans to organise peaceful demonstrations in Ferguson if the grand jury declines to charge Wilson.
