That's some great imagery.
Peregrines are strongly territorial around their nesting sites and those bridges look like ideal nesting sites for them.
It looks like they were warning you off rather than attacking, but they can be very convincing.
They way they attack prey is to dive at high speed and knock the breath out of other birds in midair.
If they were attacking the drone, you probably wouldn't even see them coming.
A flying escort out of the area. Great vid. Good job holding your nerve and not climbing and running. Maybe consider Flight of the Valkaries for soundtrack Haha