Missouri State Troopers in riot gear stand in formation outside the Ferguson Police Department in Ferguson, Missouri, November 24, 2014.Reuters

The white police officer who shot and killed an unarmed black teenager in Ferugson, United States, earlier this year will not face any charges.

A St. Louis County grand jury declined to indict officer Darren Wilson over the confrontation that killed Brown, prosecutor Robert McCulloch said on Monday. The victim was shot six times in the head and chest despite wanting to 'surrender.'

"The duty of the grand jury is to separate fact from fiction," McCullouch said, USA Today, reported.

"The jury was not inclined to indict on any charges," said Benjamin Crump, an attorney for Brown's family, said after being informed of the decision by authorities.

Brown's family said they were "profoundly disappointed" by the grand jury's finding.

"While we understand that many others share our pain, we ask that you channel your frustration in ways that will make a positive change," the family said in a statement released by its attorneys.

A crowd of several hundred people gathered outside the Ferguson Police Department ahead of the news, and many began to scream angrily as the news of the grand jury's decision was read.

"Murderers, you're nothing but murderers," one woman shouted through a megaphone at officers clad in riot gear. "Stinking murderers."

Authorities had stepped up security in and around Ferguson ahead of the decision, and Missouri Governor Jay Nixon called up the National Guard to guard against the kind of rioting that flared in the weeks after the August 9 shooting.

(With inputs from Reuters)