The Department of Homeland Security and the FBI announced Wednesday that there is potential for attacks by anarchist extremists at the Republican National Convention next week in Tampa, according to an article from Newsy.

The federal agencies noted that there is a possibility to tie up Tampa Bay area bridges at the RNC, which could be a problem for transportation to and from the event center.

A video memo sent to officials from a supposed member of the anarchist Internet group Anonymous warns that typical protesting, such as with flowers and signs, the figure said, was no longer effective. Alleged anarchist graffiti was discovered on a rooftop near the RNC site, and a stockpile of bricks and metal pipes were also found there, the article notes.

Tampa officials also spent more than $500,000 on new khaki uniforms for the 4,000 Florida officers who will attend the event, and the police department believes the uniforms will make law enforcement more approachable, the Newsy article reports.

The RNC isn’t the only concern, however, as police in Charlotte, North Carolina, have been preparing for months for the Democratic National Convention.

The RNC begins August 27, and the DNC begins September 4.