As violence in Mexico raged with intense competition between rival drug cartels and the Mexican government, the cartels came up with a radical solution for improving their capabilities in the street.

Through ingenious engineering, and by taking a page out of “Mad Max,” cartels created so-called narco tanks.

These home-made armored vehicles, also known in Spanish as “monstruo” for their hulking size, reached peak popularity in 2011 as the Mexican military seized a garage from the Los Zetas that was being used to construct the vehicles. Four narco tanks were seized in the Mexican state of Tamaulipas in addition to an additional 23 trucks that were awaiting modification.

The Mexican military’s subsequent crack-down on the creation of monstrous forced the practice to go underground. Narco tanks are still produced, but today’s versions have their armored paneling on the inside so as to not draw unwanted attention from rival cartels and the military.

Below are some of the most impressive narco tanks from the vehicles heyday.

The behemoth versions of narco tanks were created from modified semi trucks.

Dump trucks were also modified into massive steel-plated monsters.

Even smaller narco tanks were armored almost completely with steel plates that could be upwards of 2 inches thick.

As part of further defensive measures, the tanks were usually equipped with double wheels.

Offensively, narco tanks had armored turrets and weapon bays on the side, out of which cartel members could point assault rifles.

Some vehicles were equipped with battering rams to plow through traffic and any potential roadblocks.