Fifteen people were beaten to death in an indigenous village in southern Mexico which has been plagued by a dispute over an offshore wind farm project.
The bodies of 13 men and two women were recovered by authorities in Huazantlan del Rio following a series of attacks on Sunday night and Monday morning.
Some of the victims had been tortured and burnt alive, according to the San Mateo del Mar municipal government.
Photos of several bodies were published on social media. One of the dead men appeared to have been beaten with bricks.
The feud dates back to 2012 and centres on a project to build a huge, 396-megawatt off-shore wind farm planned for a narrow spit of land in a lagoon near San Mateo.
Opposition groups from the Ikoots indigenous group, also known as the Huaves, managed to block the project, arguing it would affect their fishing, farming and sacred spaces.
Local media reported the latest violence broke out after a confrontation between municipal officials from San Mateo del Mar and members of the Union of Ikoots indigenous communities.
The Union claimed supporters of the mayor Bernardino Ponce Hinajosa ambushed them at a coronavirus checkpoint and began shooting, injuring several people.
However the municipal government blamed the fatal attacks on dissidents from the indigenous group and claimed the two women killed had been protesting against abuses by one of the suspected attackers.
Prosecutors from the state of Oaxaca have launched an investigation involving 40 detectives, 80 state police officers and 39 members of the national guard.
The attorney general’s office confirmed the deaths of 2 women and 13 men with bruises and partial burns, but awaits the results of autopsies to determine the cause.
“Recently there was a confrontation between residents of the Huazatlán del Río agency and the municipal seat,” the state government said in a statement.
It added that its presence in the area would be doubled to “guarantee security, privileging dialogue and full respect for the human rights of the population.”
Additional reporting by agencies