when there are many groups in a place

[alpacinou]

I want to describe a situation where there are many groups of something in a place. Is there an idiom that I can use for that?

This is a very dangerous city. There are many different groups of criminals and gangs roaming the streets.

I'm hoping I can find an idiom to replace the underlined part with.

 

[tedmc]

(infested with) mafias?

 

[Skrej]

Criminals "run rampant" throughout the city.

Or if you want to focus on groups, then replace 'Criminals' with something like 'gangs'.

 

[alpacinou]

Can I say something like this?

The city is a who's who of gangs and drug lords.

 

[Tarheel]

I think "infested with gangs" might work better.

 

[Tdol]

With dozens of gangs