The FBI arrested two alleged New Black Panther members on Thursday on outstanding warrants, they’re “accused of purchasing explosives they apparently planned to use during protests in Ferguson, Missouri, a law enforcement source told CBS News.”

It’s believed they planned to use the explosives in pipe bombs. The men are said to be from the St. Louis area and were arrested as part of an FBI undercover operation. 

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

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.