They would have been called, not the military Predators. CBP Predators are sometimes called for help when local aviation assets are unable to help and the threat is significant.
Here are a couple of DHS websites on their Predators:
http://www.cbp.gov/xp/cgov/border_security/air_marine/uas_program/
http://www.cbp.gov/xp/cgov/border_security/air_marine/air/aviation_asset/predator_b.xml
Predator ops in the US -- other than testing and development flights in restrcitected airspace, military training flights (in MOA range airspace), and CBP operations along the border, there are no other agencies that have approval to operate within the US
The approval to operate a Predator outside FAA approved airspace is a real chore, almost impossible, as the FAA is slowly integrating UAVs and they don't, EVER want to (and who can blame them) have a mid-air with an unmanned aircraft.
Where they are deployed? Training for CBP Air and Marine and the USAF is in Grand Forks, ND, and there are Predators at Davis-Monthan Air Force Base, Tuscon, and I think there are a couple of other locations but can't say for sure. Might be one someplace down south along the east coast or in Florida, but don't know.