Updated

Gunmen attacked Oaxaca's university radio station, authorities said Sunday, the latest incident in a wave of confrontations and protests that have driven many tourists out of this historic Mexican city.

Assailants fired rounds of ammunition into the station's windows while it was broadcasting late Saturday, the Oaxaca state government said. Nobody was hurt in the attack.

Witnesses said the attack was carried out by at least 10 assailants wearing ski masks.

CountryWatch: Mexico

The university radio station has supported a wave of protests aimed at ousting Oaxaca state governor Ulises Ruiz, who is accused of rigging the 2004 election to win office and of violently repressing dissent.

Teachers Union leader Enrique Rueda, one of the protest leaders, accused Ruiz of being behind the shooting. "(Ruiz) has always responded to popular protests with aggression, threats, repression, and authoritarianism," Rueda said.

However, Ruiz's office condemned the attack and said the state government was trying to negotiate with the protesters.

Dozens of protesters, including teachers, students and leftist activists, went with sticks and stones Sunday to guard the radio station.

The protests erupted in late June after police attacked a demonstration of striking teachers looking for a wage increase. Since then, thousands of demonstrators have camped out in the center of Oaxaca, spraying buildings with revolutionary slogans, smashing hotel windows and building makeshift barricades.

The protests have paralyzed one of Mexico's top cultural tourist attractions, where visitors normally browse traditional markets for Indian handicrafts, hike ancient pyramids and stroll along cobblestone streets to sample mole dishes.

Tourism is down by 75 percent, costing the city more than $45 million, according to the Mexican Employers Federation. Business leaders have asked the federal government to intervene.