WASHINGTON (AP) — The Associated Press has learned the FBI is operating a small air force with scores of low-flying planes across the country carrying video or, at times, cellphone surveillance technology.

The surveillance equipment is generally used without a judge’s approval, and the FBI says the flights are for ongoing investigations. The planes can also capture video of unrelated criminal activity on the ground as evidence for prosecutions.

In a recent 30-day period, the AP found the government flew above more than 30 cities in 11 states across the country.

The FBI said the surveillance flights comply with agency rules that limit the types of equipment the agency can use, as well as the justifications and duration of the surveillance.