International Desk

At least 19 people were killed, four of them Guatemalans, in a turf battle between two drug gangs in the southern Mexican state of Chiapas, authorities said on Monday.

A cargo truck was found with 16 men shot dead inside, while three others were found dead outside the vehicle, the ministry of public safety said in a statement, after initially giving a death toll of 20.

The events occurred Friday in the municipality of La Concordia, near the border with Guatemala, where violence has been on the rise in recent years.

An initial investigation said the clash was between the Sinaloa cartel, one of the most powerful in Mexico, and another gang identified as the "Chiapas and Guatemala" cartel.

The ministry said in a statement that the two groups were battling over "criminal control of the border area."

The region is key for the trafficking of drugs, arms and migrants toward the United States, according to the non-governmental organization Insight Crime.

The Mexican government deployed an additional 1,200 personnel to reinforce the country's southern border with Guatemala.

In that part of Mexico, another cartel in a turf war with the Sinaloa outfit -- Jalisco Nueva Generacion -- is known to be operating.

Violence has escalated in recent years in Chiapas state.

During the country's presidential campaign, Claudia Sheinbaum -- who was elected in June and will take over from Andres Manuel Lopez Obrador in October -- was briefly detained by hooded men who stopped her vehicle. She was unhurt in the incident.

Voting was suspended in two municipalities in Chiapas state due to a spike in violence that prevented polling booths from being set up, officials said.

Spiraling criminal violence has seen more than 450,000 people murdered in Mexico since the government of then-president Felipe Calderon launched a military offensive against drug cartels in 2006.