URGENT: Five people described as anarchists were arrested Monday in a Cleveland-area park for trying to blow up a bridge, sources tell Fox News.      

The public was never in danger from the explosive devices, which were inoperable and controlled by an undercover FBI employee, according to sources close to the investigation. 

A criminal complaint was filed Tuesday morning in U.S. District Court in Cleveland, according to an FBI press release. 

Court documents say three of the suspects are self-proclaimed anarchists who formed a small group and considered a series of plots over several months.

According to the complaint, the suspects initially planned to use smoke grenades to distract law enforcement so that they could topple financial institution signs atop high rise buildings in Cleveland. However, the plot later called for the use of C-4 explosives, authorities said. The final plan allegedly named the Route 82 Brecksville-Northfield High Level Bridge, which crosses from Brecksville to Sagamore Hills, as the target.  

The FBI and the federal Joint Terrorism Task Force are involved in the investigation.

"The safety of the citizens of the Northern District of Ohio is and continues to be our primary focus," Stephen D. Anthony, Special Agent in Charge of the Cleveland Division of the FBI, said in a statement Tuesday.

"The individuals charged in this plot were intent on using violence to express their ideological views. The Joint Terrorism Task Force will continue to be vigilant in its efforts to detect and disrupt any terrorism threat, domestic or international," Anthony said. 

It is unknown if the bridge incident was connected to Occupy Wall Street's plans for nationwide protests Tuesday.