FBI arrests 2 men who planned to use explosives in Ferguson protest

The FBI arrested two men Thursday night accused of purchasing explosives they apparently planned to use during protests in Ferguson, Missouri, a law enforcement source told CBS News.

The men, who live in the St. Louis area, are allegedly members of the new Black Panthers. They were arrested as part of an FBI undercover operation near Ferguson and intended to use the explosives in pipe bombs, the source confirmed.

The suspects, whose names were not released, were arraigned in federal court on Friday.

FBI spokeswoman Rebecca Wu told CBS News the suspects were arrested on outstanding warrants.

Within days, a grand jury investigating the Aug. 9 shooting death of unarmed black teenager Michael Brown is expected to decide whether white Ferguson police officer Darren Wilson should face criminal charges.

The FBI said Friday it has deployed about 100 agents to the St. Louis area ahead of the decision, in case demonstrators take to the streets as they did after Brown's death.

St. Louis County Executive Charlie Dooley said Friday that police, government leaders and protesters have met in recent weeks to discuss so-called \"rules of engagement\" if protests arise.

Brown's family, President Obama and Attorney General Eric Holder have urged the community to remain calm, no matter what the grand jury decides.