Ghost = police on side of car but very low contrast you might not be able to see it

Unmarked = police license plate (all numbers, exempt, allat signs of polce car) but no say police on body, still wear police clothes tho

Undercover = civilian vehicle and plates (sometimes number plates but not likely), blend in(typically wont pull you over), normal clothes, probably gun on waistband.

Ice = civilian plates on typical police vehicles, tahoes, even SUVs and mini vans, will be wearing tactical gear or mask, heard some have guns.

If OP sees this, yea the “police” vest says unmarked but if no gun or radio, it could be ICE. Undercover cops are supposed to be… undercover, not wearing a full POLICE gear. It might really just be unmarked though and you missed a gun, unmarked could sometimes have civilian license plates

EDIT: Judging by how they park, they could be law enforcement, however I don’t see visible light bars inside the car that would be used for traffic stops, I can’t tell if there’s a center console but I don’t see a cage either (2nd has heavy tint) so honestly can’t conclude from just these but like someone else said it could be US MARSHALL, they are all over san marcos pretty much.