Did you hear about the Gang War script made by Kerosini? It's a basic script that spawns peds on 2 teams and they'll fight eachother. It's quite simple but it's enough to make some epic shootouts and combats. I usually use it to make videos about epic combats. Since the author made his script free for everyone who wants to mod & redistribute it, i'll upload my modifications of it (changing the peds, etc).

This is the original script by Kerosini: https://www.gta5-mods.com/scripts/gangwar-zip

Usage: you have place 2 spawnpoints on the map, one for each team (A & B). Team A is the enemy, Team B is ally. Press H to define Team A (enemy) and press J to define Team B (ally). The combat won't end until you close your game or reload the NET scripts (with Insert key).

Dependencies & installation: You need the ScriptHookV of course, and the ScriptHookV DotNET (script works with the lastest version and previous versions as well). Put ONE of the .cs scripts on the Grand Theft Auto V/scripts folder (with one i mean one at each time, if you want to change the file remove the previous one and place another one, and then restart the game or press the Insert key to reload ScripthookV.NET scripts).

GANGWAR VERSIONS

• 
  Gangs vs. Cops: a coallition of gangs from LS (Ballas, Families, Vagos & Lost MC) fights against all the security forces (LSPD, Sheriff, Rangers, the Army, FIB, NOOSE...). The player is on the gangs team. Game-spawned cops (due to having a wanted level) won't fight against script-spawned cops and soldiers. Cops use the Carbine Rifle, and Gangs use the Assault Rifle (AK).
• 
  Cops vs. Gangs: like the previous one, but the player is on the cops team. Cops spawned by the script won't shoot the player, but you should use a trainer to avoid getting a wanted level (i think i could do that with a line on the script, i should try it on a later version). Cops use the Carbine Rifle, and Gangs use the Assault Rifle (AK).
• 
  Cops vs. Gangs v2: like the previous script, cops vs. gangs -without army soldiers- but with some improvements: now you can enable or disable ped spawning by pressing the K key. But this is quite buggy, by default the script stops spawning peds when each time has a certain number of them alive, on this v2 script they haven't got that limit (i have to improve that), so be careful and remember to manually stop and resume and stop again the spawning! if not, your game will crash since they're lot of peds fighting. You can also put 2 weapons for each team, with a probability system (the code is quite shitty but works), and choose if you want the dead peds to be removed or not. Another nice change: peds from both teams will now run to the enemy objective! So don't see them walking slow as shit anymore!
• 
  Families vs. Lost w/ Muskets: a weird scenario i made. Player is on the Lost MC team, fighting against the Families. Both teams use muskets.
• 
  Families vs. Ballas: player is on the Families team. Both teams use Assault Rifles (AK).
• 
  Families vs. Ballas w/ Knives: as the previous one, but on this one both teams will use knives to fight, making a classic street fight instead of a shootout.

HOW TO CHANGE OPTIONS
On all the scripts they're some settings you can change. Open the .cs script with a text editor like Notepad, Notepad++ or Sublime Text. You can change these settings:

• • model_names.Add("pedmodel"): separated on teamA and teamB models. Just add or remove lines to place more or less ped models. Write like as given. You can see the ped models names here: https://pastebin.com/H7wK40rR (ignore the weird number combinations after the = ).
  • Weapons: locate the line ped.Weapons.Give(GTA.Native.WeaponHash.AssaultRifle, 1, true, true);, depending on the script it can be placed once or more times. Just a line = the same weapon for all the peds. 2 times = all the peds from each team will carry the same gun. Change the "AssaultRifle" for other gun you want, from this list: https://pastebin.com/bygZwqrZ (ignoring the "Weapon_" and the weird number combinations after the = ).

HOW TO CHANGE v2 OPTIONS

• • The v2 scripts (at this moment only the Cops vs. Gangs v2) have some extra options that can be modified:

• • • bool activar = true/false: choose if you want the spawning system turned on by default [true=yes, false=no]
    • -bool deletepeds = true/false: choose if cleaning death peds [true=yes, false=no]
    • Weapon probabilities: each team will have a probability and 2 weapons to choose. The int weaponTeamA = r.Next(1, 3) line will give the probability for the 1st gun. For example, (1,3) means 1 of each 3 times the 1st gun should spawn, and the other 2 times peds should spawn with the 2nd gun. JUST CHANGE the last number, the first one have to be 1. What this does is generate a random number between the numbers given; if the randomized number is 1, it will spawn the 1st gun; if it isn't 1, will spawn the 2nd gun... that's why the 2nd gun will have more probabilities to spawn than the 1st gun, if you put 1,3, 1,4, 1,5...

CHANGELOG

• • • A: initial release.
    • 
      A.1: uploaded a new script ("Cops vs. Gangs v2"), basically is the "Cops vs. Gangs" but with new functions.