By Daniel Wallis
FERGUSON Mo. (Reuters) - Police and protest organizers laid the groundwork on Friday for steps to avert street violence once a St. Louis-area grand jury decides whether to indict the white police officer who fatally shot unarmed black teenager Michael Brown in August.
Against the backdrop of heightened tension, the FBI arrested two men suspected of buying explosives they intended to detonate during demonstrations in Ferguson, Missouri, a law enforcement official told Reuters.
In a sign that a grand jury decision is imminent in the Brown case, prosecutors told media organizations they were making plans for a news conference to announce the outcome, although the date, time and location remained undetermined.
A 12-member St. Louis County grand jury has been weighing evidence on the disputed circumstances of the Aug. 9 slaying of Brown by police officer Darren Wilson in Ferguson, a predominantly black suburb of 21,000 people. The panel met behind closed doors again on Friday.
Lawyers for Brown's family say the youth was trying to surrender when he was gunned down, and a companion has said Brown, 18, had his hands raised. Wilson's supporters insist he shot Brown in self-defense.
The killing instantly became a flashpoint for strained U.S. race relations, triggering weeks of sometimes violent protests in Ferguson calling for the arrest of Wilson. He has instead been placed on administrative leave and gone into seclusion.
President Barack Obama added his voice to the chorus of politicians, civic leaders and activists appealing for calm ahead of the grand jury decision and renewed protests that are expected to follow.
"I think first and foremost, keep protests peaceful," Obama said during an ABC News interview taped for Sunday's "This Week" program.
"This is a country that allows everybody ... to protest actions that they think are unjust," he said. "But using any event as an excuse for violence is contrary to rule of law, contrary to who we are."
SPECTER OF VIOLENCE
The specter of violence was raised again by news that two reputed members of a militant group called the New Black Panther party were arrested in the St. Louis area in an FBI sting operation.
As initially reported by CBS News, the men were suspected of acquiring explosives for pipe bombs they planned to set off during protests in Ferguson, said the law enforcement official, who spoke to Reuters on condition of anonymity because he was not authorized to publicly discuss the case.
The official said the men have been named in a newly unsealed federal indictment returned on Nov. 19, charging Brandon Orlando Baldwin and Olajuwon Davis with buying two pistols from a firearms dealer under false pretenses.
Some activists decried the timing of the arrests, suggesting they were aimed at either smearing protest organizers or justifying what was expected to be a heavy law enforcement presence once protests take place. Others welcomed the news.
"Well, the Feds are protecting us from these crazies," prominent activist Bassem Masri wrote on social media website Twitter.
At a news briefing by politicians and law enforcement on preparations for expected demonstrations, St. Louis Mayor Francis Slay said he did not know when a decision would be revealed, "but we expect it will be coming very shortly."
The nearby Jennings School District said it would close on Monday and Tuesday, for fear of unrest in Ferguson, although the Ferguson-Florrisant school district planned to keep its schools open.
Activists held a news conference at a church in Ferguson on Friday to announce plans to deploy more than 50 volunteers, dubbed "Disciples of Justice," who will mill about protesters to help diffuse tensions on the street.
"We want the community to know we've got an extra set of eyes and ears in the midst of the demonstrations," said Brown family attorney Anthony Gray.
Hundreds of civil rights lawyers were descending on Ferguson to monitor any protests and ABC News reported the FBI had sent 100 agents to the St. Louis area.
Mayor Slay said police had orders to exercise restraint, to avoid stoking violence.
"We have instructed our police officers to protect the protesters' constitutional rights," he said. "We have directed them to use more active tactics only when necessary to keep people safe or to protect property."
Missouri Governor Jay Nixon has declared a state of emergency and called in National Guard troops to back up police. Groups across the country have said they would take to the streets again in large numbers if charges are not brought.
(Additional reporting by Julia Edwards and Emily Stephenson in Washington, Steve Holland in Las Vegas and David Bailey in Minneapolis; Writing and additional reporting by Steve Gorman in Los Angeles; Editing by Will Dunham, Mohammad Zargham and Clarence Fernandez)