Missouri law enforcement are bracing themselves for possible riots if a Ferguson officer is not indicted for the shooting death of 18-year-old Michael Brown, Reuters reported.

A grand jury is currently hearing evidence to determine if Ferguson officer Darren Wilson should face criminal charges for shooting the unarmed black teenager in August.

For weeks, riots and protests broke out across Ferguson expressing outrage at what civil right leaders called the death of another unarmed black male at the hands of a white officer.

With the grand jury decision expected in November, officials from Missouri State Highway Patrol, St. Louis county and city authorities and Ferguson police are drawing up contingency plans and meeting two to three times a week, unnamed sources familiar with the discussions told Reuters.

FBI officials are also involved in the meetings.

Police fear another wave of looting and violence could spread from Ferguson to other parts of the country if the grand jury chooses not to indict, St. Louis County Police Chief Jon Belmar told Reuters.

"The unrest is going to be far beyond the city of Ferguson," added Ferguson Mayor James Knowles, who is also attending the meetings.

Conflicting accounts surround what actually happened the night Wilson shot Brown several times in the chest and head. Police say Wilson and Brown got into an altercation when the officer asked him to walk on the sidewalk and not in the street on Aug. 9.

But witnesses say Brown had his hands in the air and was running away when he was shot.

Residents of the mostly black suburb are also bracing for the decision. While black residents still hold protests outside the police station, many feel the Ferguson officer will not be charged, as is the case with the majority of on duty police officers who shoot civilians.

Meanwhile, local tensions are high between white and black residents. Gun store owner Adam Weinstein said he's seen a 50 percent increase in sales since Brown's death. Most of his customers are white residents buying weapons to protect themselves in the event of more riots, Weinstein told Reuters.

"They are afraid the city is going to explode," Weinstein said.