I'll fill you in.
How it works is All ambulances except a couple BLS rigs are EMT/Medic. Medic techs ALL calls. All fire depts except for one very small one in the mountains are EMT-B's, no medics. It is in our county protocols that when we show up on scene, even as BLS, we take over medical control. On the scene of an arrest, for example, fire would be doing compressions while I would assist the medic in setting up ALS things, as we have more familiarity with the equipment. Our medics have a lot of leeway on how the call is ran, and they are the ones that are directing the scene, while performing all ALS interventions. You will rarely run on a scene with more than one medic. It works very well. This isn't to say that we are better than fire or anything else, but it works pretty much the opposite in LA County.
So basically, the sequence looks like this:
Fire arrives at call and starts BLS measures.
We arrive and take over scene, fire gives report.
If needed, fire stays or rides with us for extra hands.
Also, we are first in quite a bit.