At least eight people identified as members of the ruling National Action Party (PAN) died in a road accident in southern Chiapas state on the eve of state elections, officials said Sunday.
The Saturday night crash of a pickup truck appeared to be an accident, and not politically motivated, said PAN official Alberto Archila to local media.
The brakes of the truck, which were carrying 12 PAN members from the town of Escuintla to Chiapas capital Tuxtla Gutierrez, appeared to have failed to function. The truck ran off a mountain road and fell into a ravine in Escuintla.
State elections were held Sunday in Chiapas. Some 2.7 million citizens were registered to vote for 118 mayors and 40 seats in the region's legislature.
The accident also killed two minors, said Archila. The remaining four traveling in the truck were injured.
Officials said earlier that six people had died in the accident.
The state government has boosted security in 14 of the state's towns after gunmen killed a candidate for the left-wing Revolutionary Democratic Party in the town of Venustiano Carranza.