Air Force base in El Segundo. Allegedly a guy with a backpack that had wires hanging from it was spotted so they shut down the neighborhood.
From Ars Technica:
A California man who has been arrested several times for recording police from the ground has now taken to the airways, using a drone to watch the watchers.
“It’s to try to promote transparency,” 42-year-old Daniel Saulmon told a Los Angeles news broadcast.