Three people were killed and three others wounded in a shooting at a polling place in the southeastern Mexican state of Chiapas involving supporters of rival political parties, prosecutors said.

The shooting occurred Sunday afternoon in Rincon Chamula, a community outside the city of Pueblo Nuevo Solistahuacan, while people stood in line to vote in Mexico's general elections, the Chiapas Attorney General's Office said.

"Supporters of the Institutional Revolutionary Party (PRI) and Mexican Green Party (PVEM) were involved, incited by the municipal candidates from both parties," the AG's office said in a statement.

A woman trampled by the assailants as they fled the polling place was among the injured, the AG's office said.

The three people hurt in the incident are listed in stable condition at a hospital, the AG's office said.

A fight sparked by a traffic incident involving PVEM and Party of the Democratic Revolution, or PRD, members in Rincon Chamula last Thursday left four people wounded.

Several serious incidents were reported ahead of Sunday's general elections in Mexico.

Luis Antonio Contreras, a councilman from the PRD, was murdered Saturday in a city in central Mexico.

Contreras served on the council in Valle de Santiago, a city of some 100,000 people in Guanajuato state.

Media reports differed on how Contreras was killed, with some outlets reporting that he was killed during an argument, while others said gunmen opened fire on him from a moving vehicle that did not have tags.

PRD officials blamed supporters of the rival National Action Party, or PAN, for the killing, but this information has not been confirmed and some reports said the murder may be linked to a personal matter.

Valle de Santiago is run by the PRD, but Guanajuato is governed by the PAN.

Cesar Garibay Gutierrez, the PRI mayoral candidate in a city in Guerrero, was kidnapped on Saturday night, beaten and released a few hours later, police said.

Garibay Gutierrez, who was running for mayor of Marquelia, was found early Sunday by community police officers.

The mayoral candidate was spotted around 4:00 a.m. in the city of San Luis Acatlan, the Regional Community Authorities Coordinator said.

Garibay Gutierrez was found at a place about 30 kilometers (18 miles) from where he was abducted.

The PRI mayoral candidates in Apaxtla de Castrejon and Tixtla, two other cities in Guerrero, were also kidnapped and later released in recent days. EFE