OAXACA, Mexico – Nine people were ambushed and killed in Santiago Choapan, a city in the southern Mexican state of Oaxaca, in a politically motivated attack, officials said.

The ambush occurred Saturday morning on a dirt road as the victims were heading from the community of La Tani toward Santiago Choapan to work on final preparations for a special election in that city, a Oaxaca state Government Secretariat spokesman said.

The municipal elections in Santiago Choapan were annulled last year due to irregularities, the spokesman said.

State police chief Cesar Alfaro and Deputy Government Secretary Oscar Cruz flew to the city by helicopter to get a firsthand look at the situation and begin the investigation.

Two groups, one led by the family of former state legislator Damaso Nicolas, a member of the Institutional Revolutionary Party, or PRI, and the other advised by leftist Party of the Democratic Revolution, or PRD, member Cesar Mateos, have been fighting for control of the mountain city, which is near the border with Veracruz state.

Nicolas is a “chieftain because his family has always had power, and now that other actors want to participate, they are against it and we blame them for the violence,” Mateos said.

Oaxaca is not only one of Mexico’s poorest states, but it is also the state with the largest Indian population in terms both of absolute numbers and as a proportion of the total inhabitants.