Criminals are increasingly using drones in illegal activity and as a way to counter surveil and disrupt the FBI and other law enforcement agents, according to a report by Defense One.

The publication cites one instance where an FBI hostage rescue team set up a raised observation post to monitor a situation. A so-called “swarm” of small drones appeared and assailed the FBI in a series of “high-speed low passes at the agents in the observation post to flush them.” That incident was shared by Joe Mazel, head of the agency’s operational technology law unit at the AUVSI Xponential conference in Denver. Mazel said the FBI agents lost situational awareness. “We were then blind. It definitely presented some challenges.” Swarms of drones were also used to surveil the FBI agents and send video back to other gang members. Mazel declined to elaborate on where or when that incident took place, but said the suspects packed the drones in backpacks and brought them to the area, anticipating the arrival of the FBI.

“That activity has effectively been replaced by drones.”

The incidents illustrate how organized crime groups are increasingly using small consumer drones in support of their activities. Other notable uses include identifying witnesses by surveilling police departments to see who comes and goes from those facilities, and in support of robberies by observing gaps in security patrols and other vulnerabilities at target locations. Mazel also said that drones were being used in smuggling schemes in Australia to monitor port authority workers. The crime groups would force distractions like a false alarm if border guards get too close to a container that contains smuggled goods. Unauthorized drones have also been known to smuggle contraband into prisons.

Associate chief of US Customs and Border Protection Andrew Scharnweber told Defense One drones are also being deployed as scouts to spot their officers. “We have struggled with scouts, human scouts that come across the border. They’re stationed on various mountaintops near the border and they would scout… to spot law enforcement and radio down to their counterparts to go around us. That activity has effectively been replaced by drones,” he said.

Defense One notes there is some recourse in battling criminal use of drones. Drone jamming equipment has been deployed by the US military in Syria and Iraq, though those techniques would likely not be appropriate for use in cities given the risk of interference with mobile phone and airplane signals. There are legal options, like requiring drones to broadcast their operator’s identity, or to make “weaponized” consumer drones illegal. There are also anti-drone guns that jam all possible radio frequencies a drone can use to communicate with the operator, forcing it to land or return home. They remain illegal under FCC laws, though.

Government officials who spoke at the conference noted that the use of drones in criminal endeavors would likely get worse before it got better.