Tampa police say they've confiscated bricks and pipes from a rooftop in Tampa, and discovered what they say is "anarchist" graffiti.
The anonymous symbol was spray painted, along with the number "99" in red paint.
All of it was found on top of a building at 1000 North Florida Ave., which is at the corner of Florida Avenue and Tyler Street.
"We are appreciative that the business owner called us," Tampa Police Chief Jane Castor said Tuesday afternoon.
"Finding those items for us was not a surprise," she added. "We are just pleased to see the communications process worked the way it did."
Bill Warner is a private investigator who tracks and researches radical groups all over the world. He says the stockpile is a sign of trouble ahead.
"These are tactics terrorists use in the Middle East. They will hide bricks in piles in buildings and so forth. They will move into the area start their little protests. Then they will find their pile of bricks and pipes and start busting out windows," Warner said.
Castor said what's most important is making sure none of the items is used to harm anyone during the RNC.
For months, FOX 13 has been reporting about the Black Bloc, an anarchist group that causes chaos and havoc around the world. The FBI has labeled them domestic terrorists who are against government, corporate America, and law enforcement.
Recently cyber hackers known as Anonymous sent out a call to action for Black Blockers to unite at the RNC. Their message to Chief Castor and the media was simple: they're coming to Tampa to fight for what they say are their rights.