At least four suspected gunmen died in a shootout with marines in the central Mexican state of Zacatecas, where a wave of drug-related violence has claimed the lives of nearly 30 people in the past few days, officials said.

The shootout occurred Monday morning on a highway in the city of Fresnillo when a group of heavily armed men tried to evade marines who were on patrol in the area, officials told Efe.

The bodies of the four dead gunmen were found inside an SUV after the shootout.

Gunmen from rival cartels, meanwhile, engaged in a shootout Monday afternoon in the city of Tepetongo, but no casualty figures are available, Zacatecas Attorney General's Office spokesmen said.

Eight decomposing bodies showing signs of torture were found last Friday in an SUV that was abandoned outside Fresnillo.

A total of 15 suspected gunmen were killed and 14 others arrested in different operations staged by the security forces in Zacatecas.

These incidents occurred amid a turf between rival drug cartels, including Los Zetas and the Gulf cartel.

More than 50,000 people, according to official figures, have died in drug-related violence in Mexico since late 2006.

The Movement for Peace with Justice and Dignity, which was founded by human rights activist and poet Javier Sicilia, puts the death toll at 70,000.

The violence has spiked this month, with the Mexico City daily Reforma reporting Saturday that 231 people were murdered across the country from Aug. 4 to Aug. 10, raising the death toll for the year to 6,309. EFE