Air carrier pilot reported abruptly braking to avoid a collision with an airport vehicle while taxiing that was escorting two other vehicles.

Narrative

Entering ramp area on Y2 taxiway (with clearance from ramp to enter for gate XX); an airport pickup truck that was escorting two unmarked civilian" vehicles drove directly in front of us. The pickup truck accelerated on the vehicle road from left to right driving in front of us while the two other vehicles had the good sense to stop. I was required to aggressively jump on the brakes to stop the aircraft just short of the road. We reported the incident to MIA Ground Control and they confirmed they saw the vehicle in question. We continued to the gate and parked.Irresponsible wreck less driving behavior by the vehicle in question. Everyone knows that aircraft have the right of way while driving around an airport. This was simply dangerous conduct that could have resulted in a collision or injury to Flight Attendants who happen to be up while taxi operations are happening.Follow up with the MIA airport operations department to determine the driver of the vehicle and take appropriate action. MIA flight office follow up with the airport and emphasize the possible consequences of a ground accident like this potential one. Far too often these types of incidents are reported but never followed up on. Removal of badges and driver privileges for airport vehicle operators would send the message to slow down and follow the rules of the road."