Troops from the Missouri National Guard prepared to deploy on Tuesday around Ferguson on Tuesday as the city awaits a grand jury's decision on whether to indict a white police officer who shot and killed an unarmed black teenager in August.

Governor Jay Nixon has declared a state of emergency in Missouri but said troops would play a backup role to police in response to any protests that develop after the decision.

A demonstrator takes part in a protest over the shooting death of Michael Brown in front of the Ferguson Police Department in Ferguson, Missouri, Nov. 17, 2014.