Gone are Oaxaca's familiar nighttime sounds of tinkling marimba music and vendors hawking chocolate or traditional fried grasshoppers, replaced by gunfire, the roar of burning tires and shouts from bands of men armed with clubs.

Protests in this picturesque colonial city that began with a teachers' strike in May have ballooned into a political battle against state Gov. Ulises Ruiz.

CountryWatch: Mexico

Some 40,000 teachers, as well as leftists, student groups and anarchists have set up hundreds of roadblocks, seized the city's central plaza and covered businesses, homes and historic buildings with graffiti. They refuse to give up until the governor resigns.

The group leading the protests said Thursday it would accept an offer from President Vicente Fox's government to negotiate an end to the conflict, but only if state officials were not included.

Oaxaca city, the capital of a state of the same name, is ordinarily one of Mexico's premier tourist destinations. But the U.S. State Department has said rising political violence might make Oaxaca too risky for Americans to visit.

Protesters have hijacked some city and charter buses and burned others, taken over radio and television stations, blocked government buildings and forced many businesses here to close. Two protesters have been shot to death.

Blaming those deaths on state forces, demonstrators have begun burning piles of tires at night to keep police away and organizing groups of men armed with clubs to patrol the city in an effort to protect their movement.

Radio stations they have seized broadcast unconfirmed reports of new shootings nightly. At any hint of danger, protest leaders ring church bells, calling their supporters from their beds to the streets.

"Nights here in Oaxaca have become nights of terror," said Cerves Nunez, a striking teacher who was overseeing operations at Radio Ley, a station seized by hundreds of protesters who are now living on the premises.

Ruiz's government says all police have been ordered off the streets until the protests end and denies that its forces were behind the shootings.

The governor became the protesters' central target after state police unsuccessfully attempted to disperse protest camps in the central plaza on June 14. The governor belongs to the Institutional Revolutionary Party, which has governed the state since 1929.

Nunez said that even if the state meets the teachers' original demand for a 20 percent salary increase, Ruiz still must go.

"The demand of the teachers have become secondary," he said. "The community is organizing against Ulises Ruiz exclusively."

Interviewed in a makeshift protest camp erected in Oaxaca's leafy central plaza, protest leader Roberto Garcia said demonstrators would travel to Mexico City for negotiations to resolve the standoff as long as they are mediated by Fox's top Cabinet member, Interior Secretary Carlos Abascal.

But, Garcia said protesters won't drop demands for Ruiz's ouster and will only agree to negotiations if the governor and Oaxaca state officials are barred from attending.

Oaxaca state spokesman Miguel Concha read a statement to the news media saying officials were in favor of using "dialogue to resolve the conflict that the city of Oaxaca is living." He did not take questions or respond to protesters' demands that state officials not be involved in negotiations.

Fox's government has sent two sets of envoys to Oaxaca in recent months to negotiate a settlement, but the dialogue broke down.

Construction worker Ricardo Acevedo, one of about 300 people blocking a major intersection, said many here are also angered by the state's sale of forests outside the city to private companies who have cut down thousands of trees.

"This is a movement of thousands and thousands of people," said the 44-year-old. "We don't have guns, just a lot of heart. But our hearts can hold out for a long time."

Classes began for students across Mexico on Monday, but public schools remained closed for 1.3 million children in Oaxaca, even as striking teachers continue to draw state salaries.

Tourism is Oaxaca state's top revenue source, but violence and fear have left little room for this city's traditional folklore.

Fredy Alcantara, president of the Oaxaca hotel association, said that the tourism industry has lost $150 million since striking teachers first seized the central plaza on May 22. He said city hotel occupancy rates are at about 10 percent and that three downtown hotels have shutdown temporarily, one after it was occupied by protesters.

"We can't say to people, 'Come visit us' because the city is incomplete, it isn't ready to offer visitors what they deserve," said Alcantara. "There's no danger for tourists. But it's sad that they will see a city that's dirty and lawless. A city in conflict."