There's a state of emergency in Missouri because of concerns about possible violent protests in the Michael Brown case. As Michelle Miller reports, FBI warned police departments across the country to be alert.

The grand jury's decision is imminent, and will come from the prosecutor's office in Clayton, Missouri, where protesters have been assembling each day.

While community leaders here are preparing, protesters see the activation of the National Guard as a sign they will not get what they want -- an indictment.

"It's almost like they're preparing for war," Pastor Robert White said.

He met with protest organizers at the Greater St. Mark Family Church in Ferguson to discuss the governor's declaration.

"We believe we have the right to assemble until we're told we can't," White said. "But we're just telling them to be careful, to be safe, allow yourself to protest, allow yourself to express your views and not to violate the law."

The executive order was signed by Gov. Jay Nixon Monday, authorizing the Missouri National Guard to help keep the peace when the grand jury decision is handed down.

"We do not want to make this look like it is a militarization of our police department," St. Louis Mayor Francis Slay said.

The mayor addressed the deployment and said the guard will be playing a "support role" to the larger "unified command."

"We feel much more comfortable having our police officers dealing directly with protestors in various settings," Slay said.

In August, the National Guard mobilized, deploying armored vehicles on the streets of Ferguson.

On Monday, protesters marched in freezing temperatures near the St. Louis county courthouse, as grand jury proceedings went on inside.

"I think that they believe that with the change of season, with the number of days that we've been out here -- 101 -- that we're going to quit, and I think that we're more passionate than ever because we're determined to see this through," St. Louis resident Kayla Reed said.

"The question is what community are they protecting? We're wondering because they said they were protecting us when they bombed us with tear gas." White said.

Slay said there is no hard number of National Guard troops that will be deployed. He is expecting their arrival by this week's end.