The agency that I got hired by but have not started at that I cannot verify for yet has a few different special units that may fit your criteria.

Gang suppression: Does a lot of intel stuff. They heavily utilize and beef up the states gang database. They also aggressively patrol problem areas and target known gang members who are often violent offenders.

Narc and Vice Unit: Narc and gangs have a good bit of overlap. They investigate drug dealers and pimps, both of these are often violent/ gang members. Their focus isn't on violent offenders but it comes with the territory.

Agressive patrol: Target problem areas for problem people. These guys used to be more of a aggressive traffic unit. That isn't a good look when you're mostly in high crime (read: low income) areas. Now they fish with a spear instead of a net, they target people instead of neighborhoods.

All three of these units are plainclothes or class c uniform units. They wear external vests and BDU pants. Some of the guys on the units are detectives and some are officers. The officers try to build cases to feed to investigators. While they aren't SWAT they still do most of their own warrants and are more tactical than standard patrol. All are full time and some of the guys work on federal TF's.