[tzs]

If we are assuming terrorists that can get real time access to government servers, we should assume they will access the servers used by the dispatchers and so can find out when an emergency vehicle leaves and where its destination is.

That is probably more useful for planning an attack on emergency vehicles.

Although why even bother with servers? Just call in a fake emergency (or cause a real emergency) at a place of your choosing, and the government will send emergency vehicles to you.