Law enforcement personnel are worried that the Pope’s visit to the United States could attract terrorist attacks and even go as far as impersonating police officers, EMTs, and firefighters to launch such attacks.

“The impersonators’ main goals are to further their attack plan and do harm to unsuspecting citizens as well as members of the emergency services community,” said the bulletin, titled “First Responder Impersonators: The New Terrorist Threat.”

The Pennsylvania State Police’s Criminal Intelligence Center distributed a memo to law enforcement throughout the northeast that imposters could use false identification to enter secure areas or to get away undetected from a crime scene. Pennsylvania State Police stated that the memo was not specifically meant for the Pope’s visit and officials confirmed that there were no credible threats known against Pope Francis at this time. The New York State Police Department and the Metropolitan Police Department in Washington also confirmed there were no known threats tied to Pope Francis’ visit.

FBI and Homeland Security reports based the premises for the memo, which made statements that suspects in the U.S. and abroad were in possession of police uniforms. In the past, authorities have arrested potential terrorists who were in possession of U.S. military uniforms, fake IDs, and police uniforms.

“A wide variety of products such as clothing, weapons and tactical gear can be purchased on the Internet by any consumer, regardless of a confirmed affiliation to emergency services, government or law enforcement agency,” the statement read. The document also advised that police be on high alert for theft of uniforms, credentials, and emergency vehicles.

Police officials are also warning citizens to be aware of their surroundings during the Pope’s visit, especially when in large crowded areas. The memo states that event locations and public transit are high risk areas because of the large groups of people and the amount of attention the city will have during the papal visit.

According to House Homeland Security Committee Chairman Michael McCaul, the U.S. has stopped at least one threat against Pope Francis last week.

During the Pope’s visit, security preparations include screening checkpoints, airspace restrictions, and a ban on selfie sticks and backpacks at the events. Along the motorcade routes there will be multiple airport-style screenings and extensive street closures in every city he visits. There will also be a significant increase in the amount of first responders deployed in the cities.