In total, there are 11 bunkers throughout the Warzone map. Each of these bunkers has different loot for the player to grab once inside, though getting inside them is the hard part.
According to the bunker map, most of them are located along the edges of the map. Only four of the bunkers are located in the central part of their respective zones. One is located southeast of the dam, and another is located east of that one, just south of the military base.
There are two more bunkers, right next to each other, just northwest of the lumber yard.
Ten of these bunkers are accessed with a red keycard, which you can obtain from looting other players. Probably the easiest way to find a keycard is to wait outside one of the bunkers and shoot anyone trying to access them. One of them is bound to drop a keycard, giving you access to the 10 bunkers and the loot inside.
The rewards for accessing these bunkers is different for each one, so guard your red key card very carefully while you navigate the rest of them.
Source : https://www.distractify.com/p/where-are-the-bunkers-in-warzone