One of those killed was the head of public works in San Fernando, Marco Samuel Herrera Rangel. The bodies of five others were found alongside Herrara's after an incident that appears to be a mass execution, the the report quoted local General Prosecutor's Office of Justice as saying.

In a separate incident, in Jimenez, a small town 97 km from state capital Ciudad Victoria, five men were found dead near a gas station at what appears to be the scene of a shootout. Three were found dead of gunshot wounds in a car and two others were lying around 200 meters from the vehicle.

The killings came a week after Mexican authorities executed Antonio Ezequiel Cardenas Guillen, leader of a Mexican drug trafficking gang called the Gulf Cartel.

Generally, murder cases tend to surge after the killing or arrest of a major gang boss.

Mexican authorities are fighting a war with the nation's illegal traffickers. So far this year, about 7,500 people have died in incidents related to drug trafficking in the country, according to statistics from the media.