This is my original siren made ready for FiveM use.

Please note that it is client side only and it can not be installed on your server for serverside streaming.

Original project:
https://www.gta5-hub.com/vehicles/danish-police-siren-mod-by-asser90

Installation:
Add RESIDENT.rpf to your game directory @ Grand Theft Auto V\x64\audio\sfx replacing the current one.

Enjoy - Asser