A rash of drone sightings during the Colorado Rockies’ first homestand of the season against the Philadelphia Phillies sent law enforcement scrambling to track down the operators.

No one was arrested after more than a half dozen drone sightings around Coors Field April 3 to April 5, but it is possible the drone pilots could still face a fine later. Still the Federal Aviation Administration and FBI issued a warning Thursday to try to keep drones away from the stadium during the Rockies’ next home games because they are concerned about the potential threat they pose.

“The illegal drone activity did not jeopardize anyone’s safety, but there were enough violations that the teams on the ground were concerned about the number of operators that did not seem to understand the seriousness of the situation. Thus the proactive messaging,” FBI spokeswoman Vikki Migoya said.

The FAA routinely restricts the airspace around major sporting events to protect the crowds and make sure the game can be played without interruptions.

The greatest fear is that someone could use a drone in a terrorist attack that could be just as deadly as the drone attacks that have become common on the battlefields of the Ukraine and Iran wars. That is why the federal government and World Cup host cities are investing hundreds of millions in drone defenses ahead of those games.

But even without a threat like that, Migoya said the problem is that illegal drone activity distracts law enforcement.

“Every instance of illegal drone activity requires a law enforcement intervention to ensure the intent is not nefarious; the fewer violations there are, the more law enforcement can focus on what might be a true threat,” she said.

All the airspace within 3 miles of Coors Field is restricted starting one hour before a game and continuing for one hour after a baseball or football game. Pilots are responsible for checking those restrictions before they fly.

The FAA said that drone operators who violated the restrictions could face fines up to $75,000 per violation and even lose their licenses.

Drones are also required to broadcast their locations. But authorities have other methods available to track down the operators.