Mexican cartels' five WORST massacres from burning down casino to bloody prison riot

The seemingly endless war on drugs that has gripped Mexico for decades has led to hundreds of thousands of deaths.

The cartels that drive the violence have been in the news once again after four Americans on their way for a tummy tuck appointment

were kidnapped leading to two of them being killed.

But since the decline of the Colombian cartels in the 1990s the rise of the Mexican ones has been almost unstoppable.

And this rise has been tied to horrific acts of violence more worthy of Genghis Khan than modern organisations.

Dismembered heads thrown into crowded bars, bodies hung from bridges are just some of the fearsome tactics used by these huge criminal gangs.

Here are five of the bloodiest massacres carried out by the cartels.

The 2011 San Fernando massacre

After unclaimed luggage began piling up at bus stations in Reynosa and Matamoros, in Tamaulipas state, an investigation was launched.

Bus loads of passengers were found to be missing, mostly migrants from Central and South America traveling to the US in search of a better life.

After extensive searched from the authorities, a horrific 193 people were found rotting in 47 mass graves.

A cartel informant later said they were terrified their rivals were bussing in more foot soldiers so moved to intercept them.

It's believed the women would be raped and killed but the men put in pairs.

They would be given sledge hammers and forced to fight each other with the survivors recruited into Los Zetas.

This mirrored a grim massacre from the year before when 72 migrants were killed in similar circumstances.

Monterrey Casino Attack

After a dispute erupted between Los Zetas and a casino in Monterrey, Mexico, a gang of cartel footsoldiers gathered to enact their vengeance.

The group ate some food before driving to a petrol station to fill containers with highly flammable fuel.

Although the gunmen tried to clear the casino many of those inside hid in fear and when the fires were lit they simply suffocated.

The next day authorities announced 52 people had died.

The attack prompted widespread public outcry and demands for greater government action to combat the violence and corruption plaguing the country.

Durango massacres

One of Mexico's grimmest mass graves was found in the upscale Jardines de Durango neighbourhood in Durango.

In all around 340 bodies were unearthed.

Many of those found are believed to be innocents as well as rival cartel members.

Iguala mass kidnapping

In a 2014 case that garnered international attention, 43 students disappeared while driving through the Iguala region of Guerrero, Mexico.

The students were traveling to a protest when they were intercepted by local police who allegedly handed them over to a drug cartel.

The students were never seen again.

Their disappearance sparked outrage across the country and exposed the corruption and collusion between the government, police, and drug cartels in Mexico.

Numerous officials were arrested on suspicion of involvement in the abduction and a truth commission tasked with uncovering what happened continues to work.

Apodaca prison riot

This bloody incident is the third time Los Zetas has appeared on this least highlighting their extreme violent techniques.

A riot broke out in 2012 at the Apodaca Prison in Nuevo León, which was packed full of rival cartel members from the Gulf Cartel and their sworn enemies Los Zetas.

By the end authorities said 44 Gulf Cartel members had been killed and around 37 Los Zetas members had escaped.

Some speculated the riot was a cover for the planned escape.