|The murder of Nuevo Leon's police chief has dealt a blow to the government's battle against organised crime [AFP]
The turf war between rival drug gangs has left a further 19 people dead after a series of shootings and an attack on a senior police commander in northern Mexico.
The city hall, courthouse and police headquarters were all damaged during the killing spree in Padilla, where seven bodies were dumped in the main square of the town, just north of Ciudad Victoria, the capital of Tamaulipas state.
A group of five people were shot dead inside their car, while one was killed during an attack on a public bus.
A further five inhabitants of the town were killed, but authorities have not yet released details.
The killings came as authorities announced on Monday that troops had arrested Juan Carlos Olivera "El Sonrics" Acosta - a suspected leader of the Zetas gang.
Officials in Nuevo Leon, which borders Texas, said the corpse of Homero Salcido Trevino, the state's police intelligence and security director, was found on Saturday night inside his burnt-out car, abandoned in central Monterrey.
Trevino had reportedly been ambushed and kidnapped as he left his home, hours before his body was found in his smouldering 4WD vehicle.
"It is still premature to tell you it was organised crime," Rodrigo Medina, Nuevo Leon's governor, said.
"What is evident is that we have a vicious fight between the cartels of organised crime, which have provoked this violence and has obligated us to redouble our efforts."
Medina said security officials know the risks they face but vowed attacks would not "force us to back down or stand aside in this fight".
Salcido's killing is a blow to federal and state governments' efforts to re-establish control over Monterrey, Mexico's business capital, which has been wracked by increasing drug violence over the past year.
His three bodyguards and chauffeur have reportedly been interrogated.
In another development, soldiers in Nuevo Leon also announced they had captured Olivera Acosta, and said he was reponsible for attacking federal police while unsuccessfully trying to rescue five members of Los Zetas, one of the four largest gangs vying for control of drug running.
The army said Olivera Acosta, who was allegedly found bearing weapons, had led criminal activities such as drug trafficking, kidnappings, robberies and killings in the Nuevo Leon municipalities of Montemorelos, Linares, Hualahuises, Rayones, General Teran and Allende since August 2010.
He is also accused of attacking a military base on February 4, 2010.
Nationwide, almost 35,000 people have been killed since Felipe Calderon, the Mexican president, launched a military crackdown against drug trafficking in 2006.