The daring and apparently co-ordinated raids in Guerrero and Oaxaca states by a recently emerged group, the Popular Revolutionary Army (EPR), stunned Mexicans and hammered the peso and stock market, which fell 50 points.
The President, Ernesto Zedillo, due to give his annual state of the nation address on Sunday, had billed the group as a "pantomime" confined to the jungled hills of Guerrero and posing no threat to the government. The group had insisted it had cells throughout the country and was fighting for a new constitution and populist economic policies.
There were no reports of tourist casualties in the Pacific resort of Huatusco, where about 80 masked rebels attacked the main square, a naval base, a federal police station and a prosecutor's office early yesterday. Three soldiers, two policemen, two civilians and two rebels were killed, according to the Oaxaca state government.
The attack could be devastating for the resort, built up from virtually nothing over the last decade in the hope of competing with the tourist resorts of Acapulco and Cancun. Most of the tourist hotels are along the beach outside the town, but the raid is certain to cause concern among tour operators.
A few hours earlier, about 60 masked guerrillas in camouflage uniforms and firing AK-47 assault rifles had appeared in lorries in the Oaxaca town of Tlaxiaco and rained gunfire on the town hall. Police commander Juan Feliciano Arango said two of his men were killed and one was missing.
The rebels fled after a one-hour gun battle and after painting slogans on houses, saying: "Long Live the EPR. With the popular struggle, it will triumph."
"There was a massive gun battle," one eyewitness said. "Everyone ran, everything turned into panic. We hid in the safest part of the house. The town lived through an hour of sheer terror."
A third assault was in the state of Guerrero, where the EPR emerged in June. Rebels attacked the police station in the town of Tixtla and riddled municipal buildings with bullet holes. At least one policeman was killed and four were wounded.
The peso slid in January 1994 after the so-called Zapatista National Liberation Army (ELZN), led by Sub-comandante Marcos, a pipe-smoking guerrilla in a black balaclava, briefly took five towns in the south-eastern state of Chiapas. More than 100 people were killed in the first two weeks of 1994 but the rebels have since retreated to the jungle and are negotiating a peace deal with Mr Zedillo's government.
The EZLN has said it has nothing to do with the EPR but some leftists believe the groups have common roots in the urban guerrilla movement which followed student-government clashes in the late 1960s.
What shocked many Mexicans was that the EPR, which had previously emerged only at a public rally and in minor clashes, appeared to have coordinated three serious assaults many hundreds of miles apart. The group also appeared to have modern and effective weapons, as opposed to the Zapatistas, most of whom had rusty, decades-old rifles.
Some feared that the latest uprising was a desperate effort by the left to recoup prestige after several years of splits and confusion on the political front. With Mr Zedillo's mighty Institutiona Revolutionary Party (PRI) in power for nearly seven decades, the left had been its greatest challenge until crumbling in the early 1990s, when the strongly Catholic right-wing National Action Party (PAN) turned into the biggest threat to the tottering PRI.