A farm group in the southern Mexican state of Chiapas said six of its members were shot dead in a confrontation with masked assailants, and members accused leftist Zapatista rebels of carrying out the killings.
Chiapas state prosecutors said they were launching an investigation into Thursday's attack, which apparently involved a land dispute. The Zapatistas are in the process of dissolving their political wing and were not available for comment.
The violence occurred near Las Margaritas, a remote rural community near the border with Guatemala.
The victims were Indians from the Center for Farmers and Farm Workers, known by its Spanish initials as CIOAC. The group claims 150 hectares (370 acres) of land the Zapatistas also say is theirs, according to CIOAC leader Miguel Angel Vazquez.
Vazquez said about 25 men wearing black ski masks opened fire with shotguns in a field where nine CIOAC members were working. He said the assailants identified themselves as Zapatistas.
Antonio Rodriguez, 35, said he escaped by running up a hill. Another two CIOAC members were seriously wounded in the violence, he said.
The CIOAC farmers support the leftist Democratic Revolution Party, which has had rocky relations with the Zapatistas in Chiapas for years, and also at the national level in recent months. The Zapatistas rose up in arms in 1994 demanding more rights for Indians, reported AP. P.T.