Four people were injured in a clash between supporters of rival political parties in the southern Mexican state of Chiapas, authorities said Wednesday.

The trouble began Tuesday night with a traffic incident involving backers of the PVEM and PRD parties, the chief of staff of the state government said.

"That led to a confrontation among partisans, (members of) the Institutional Revolutionary Party joined in later and there were gunshots," Noe Castañon Leon told reporters.

The clash was followed by an attack on the home of the mayor of Pueblo Nuevo Solistahuacan, Pablo Bautista, "who was taken away from the place to protect him," the Chiapas official said, adding that calm was restored with the aid of the army.

Three people suffered gunshot wounds and a fourth received injuries from a beating, Castañon said, while the mayor's house was burned and five other homes were damaged.

Bautista, who was elected mayor on the PRD ticket, subsequently switched to the PVEM, a coalition ally of the Institutional Revolutionary Party.

Nearly 80 Mexicans are eligible to go to the polls on Sunday to elect a president and members of Congress. Voters in Chiapas will also select 122 mayors, 41 state legislators and a state governor. EFE