Michael Brown shooting: Woman 'shot herself in the head after buying gun to protect herself from possible Ferguson verdict unrest'

The woman allegedly waved the gun and jokingly said she was ready for Ferguson

A police officer secures an area around the Buzz Westfall Justice Center in Clayton, Missouri where a grand jury is considering whether to indict a white Ferguson police officer who shot and killed an 18-year-old black teenager, Michael Brown. (JEWEL SAMAD/AFP/Getty Images)

A woman in Ferguson, Missouri is believed to have accidentally shot herself in the head and died, after she bought a gun fearing an upcoming jury decision on the shooting of Michael Brown would spark violent unrest.

Becca Campbell, 26, shot herself on Friday night in an area near a football stadium in central St Louis, the city’s Metropolitan Police Department said.

Campbell was in her boyfriend’s car when they were involved in a crash - allegedly causing the gun to go off, sources told CNN.

Her partner, who was not identified, told police that the couple had bought a gun because they feared the pending grand jury decision on the shooting of unarmed black teenager Michael Brown, 18, by a white officer, Darren Wilson, would see renewed protests in the city.

He told officers that the pair were driving late on Friday night when Campbell waved the gun and jokingly said she was ready for Ferguson, the sources added.

He then ducked out of the way of the gun, and accidentally crashed into the back of another vehicle causing Campbell to be shot in the head.

The victim was rushed to hospital, where she later died.

Police are continuing to investigate the incident to ensure her boyfriend is correct, and are awaiting gun trace results, the sources told CNN.

A prosecutor in Missouri is expected to announce today whether a grand jury has decided to indict Wilson for the fatal shooting of Brown.

Lawyers for Brown's family argue the teen was attempting to surrender when Wilson shot him, but Wilson’s supporters say he feared for his life and acted in self-defence.

Ahead of the announcement, the White House said on President Barack Obama has urged protesters to be peaceful when the decision is made public.

Brown’s death in August sparked weeks of protests in the St Louis suburb, fuelled by racial tensions.

And activist groups have vowed to re-launch street protests if officer Darren Wilson is not indicted for Brown’s death,

In response, Missouri Governor Jay Nixon has declared a state of emergency in anticipation of the ruling and called in the National Guard.

Brown's parents, ministers and community leaders have urged sympathisers to remain peaceful, whatever the outcome.