Gunmen killed a family of six, including three children, on Friday in a town plagued by militia violence in the southern Mexican border state of Chiapas.

Julio Perez, the mayor of the town of Pantelho in Chiapas, said the killings took place there on Friday and called it a “massacre.” Two warring militia groups, suspected of being backed by drug cartels, are fighting for control of the town.

It is the latest in a series of mass killings in which killers in Mexico have wiped out entire families.

On Sunday, gunmen stormed a home in the north-central state of Guanajuato, killing four women and two children.

Both Chiapas and Guanajuato, cities that share the border with Guatemala, have been hit by bloody gang conflicts in recent years.

Local media reported that gunmen entered a house in the city of Leon, Guanajuato, where they were looking for a male family member. When they discovered he had already fled, they killed the women and children.

The Guanajuato massacre has attracted particular attention because surveillance camera footage showed five National Guard officers entering the house five minutes before the killings. They left the house carrying a large black plastic bag just before the killers arrived.

On Friday, President Andrés Manuel López Obrador said five officers of the paramilitary National Guard had been detained for violations of military discipline, and were in the custody of the Defense Department, but he declined to provide further details on the case.