Governor Pleads for Calm Hours Before Ferguson Grand Jury Decision

— -- Missouri Gov. Jay Nixon pleaded for calm tonight just hours ahead of a grand jury's decision whether to indict a Ferguson police officer in the death of unarmed teenager Michael Brown.

Nixon made a brief statement as the region waited tensely for the grand jury's decision on Officer Darren Wilson, who shot and killed Brown on Aug. 9. Earlier in the evening officials said the panel had concluded its deliberations. The decision is expected to be announced at 9 p.m. ET.

"Our shared hope and expectation is that regardless of the decision, people on all sides show tolerance, mutual respect and restraint," the governor said.

Nixon said he met with local businesses and residents when he was in Ferguson earlier today. "It is understandable that, like the rest of us, they are on edge waiting for a decision, but they are doing their best to go about their daily lives," he said.

He said authorities were making sure the "best and most experienced officers" would be on the street tonight. Mental health counselors are on the scene, Nixon said, to help address "the stress these events have caused."

Authorities acknowledge that the jury's ruling could anger some people.

St. Louis Mayor Francis Slay said, "Some people are going to be angry and frustrated, and some people are going to be angry and frustrated about that."

County executive Charlie Dooley said that people's safety and the protection of private property are among law enforcement officers' top concerns.

"We are committed to de-escalating negative situations in a responsible manner," Dooley said. "I do not want people in this community to think they have to barricade their homes and take up arms."

The lawyer for Brown's family has been informed that the jury has reached a decision and law enforcement personnel are also being notified, sources told ABC News.

"The Grand Jury hearing the Michael Brown/Darren Wilson investigation has reached a decision and it will be announced later today," the office of the prosecuting attorney for St. Louis County said today.

The panel must decide whether to indict Wilson for shooting Brown at least six times during a confrontation this summer. Some witnesses said Brown had his hands up when he was shot. The police said Wilson fired because Brown was advancing on him.

The grand jury has been working on the case since Aug. 20 -- less than two weeks after the shooting -- meeting at least once every week.

The question that the jurors had to answer was whether or not there was probable cause to believe that Wilson committed a crime when he shot Brown. If they decided that he was guilty of a crime, they could consider charges ranging from involuntary manslaughter up to first degree murder, the state prosecutor's office previously reported. The jury was also informed of the state statutes towards self-defense and the use of force by law enforcement officers.

Authorities have been preparing for the decision for days and fear that the protests could turn violent, as some did in August following Brown's death. The Ferguson-Florissant School District canceled after-school activities today because of news reports that the grand jury has reached a decision and canceled classes for Tuesday. Schools are closed for the rest of the week because of the Thanksgiving holiday.

The FBI sent about 100 agents to the St. Louis area to help deal with any problems that could arise from the grand jury decision. They also released a memo earlier last week warning that extremists "will likely" try to infiltrate the demonstrations not only in Ferguson, but elsewhere around the country, and may use the verdict as an excuse to hack public utilities and other sites.

Nixon had declared a state of emergency last week and called out the National Guard.

Michael Brown's parents have made repeated calls for peace and President Obama reiterated that message this weekend.

"Using any event as an excuse for violence is contrary to the rule of law and contrary to who we are," Obama said in an interview that aired Sunday.