Six prominent Jesuit priests, including the rector and vice rector of El Salvador's most prestigious university, were killed early today along with two other persons at the house where they slept in the capital. 

The priests were the most prominent victims of Salvadoran violence since 1980, when eight leftist politicians were gunned down by the military, three American nuns and a lay worker were shot dead and archbishop Oscar Arnulfo Romero was assassinated as he said mass. 

Today's execution-style slayings, which may have been preceded by torture, took place as the government armed forces unleashed heavy air and artillery attacks on strongholds established by leftist guerrillas in the massive offensive they launched last Saturday. 

The attacks also appeared to cause more casualties among civilians in besieged residential neighborhoods. Fighting also was heavy in eastern and central El Salvador, where the guerrillas have taken positions in major cities. 

At the scene of the killing of the churchmen, a Jesuit priest said witnesses had reported seeing more than 20 armed men in uniforms enter the house between 2 a.m. and 3 a.m., apparently through a back door blown off by an explosive device. There was no fighting in the area, which was in the hands of the army and police under the state of emergency and night-hours curfew imposed by the government. 

Several of the victims had been shot in the head. Four of the bodies had been left face down in the front yard of the blood-spattered house. Several had chunks of flesh gouged out, and the brains of two of the victims shot in the head lay several feet from the bodies. 

Slain priest Ignacio Ellacuría, 59, was rector of the Central American University and a widely respected leftist intellectual who was frequently denounced by the far right who claimed he was a spokesman for the Marxist-led Farabundo Marti National Liberation Front. 

Ellacuria, who was born in Spain and later became a Salvadoran citizen, received frequent death threats and had been denounced in recent days on the national radio chain that has replaced independent local news broadcasts. 

The university's vice rector, Ignacio Martin-Baro, 50, also a Spanish-born Salvadoran citizen, was best known as an analyst of national and regional affairs and as the founder and director of the Public Opinion Institute, a highly respected polling organization. 

A sign left near the bodies said, "The FMLN has executed the spies who turned on them. Victory or death. FMLN." 

In broadcasts today, the rebel front's clandestine radio has laid the killings to a government-directed death squad and said the guerrillas would extend their offensive with renewed fury to avenge them. 

Several analysts attributed the killings to the extreme right that is generally held responsible for tens of thousands of killings in the last decade. They said the murders could signal the beginning of a campaign that could discredit the rightist government of President Alfredo Cristiani -- which the United States and some local opposition leaders recently have credited with reining in the extremists. 

"What is scaring me rigid is that the right wing is taking over," said a diplomat. "I think Cristiani has lost control." 

In the wake of the killings, the government announced that it would provide personal protection for Salvadoran Archbishop Arturo Rivera Damas. {In Rome, the Associated Press reported, the headquarters of the Jesuit order condemned "this barbarous violence that has claimed so many other victims among the people of El Salvador."} At a news conference, Cristiani condemned the "act of savagery," intended to "hurt democracy and stop the peace process" in El Salvador. He promised an immediate investigation. No investigation into death-squad activity has ever succeeded in identifying its leaders. 

Cristiani, citing the dusk-to-dawn curfew in the capital, said the killings were probably the work either of the rebels or of the armed forces. He said that broadcasts during the day by government-controlled radio blaming the FMLN for the killings were "not authorized." 

U.S. Ambassador William Walker called the killers "animals." He added, "It is an act of barbarity that not only brought shame to El Salvador but will leave a gaping hole in this country's intellectual and academic community." {In Washington, White House press secretary Marlin Fitzwater said, "We condemn in the strongest possible terms the outrageous" murders.} The killings came against a backdrop of all-out urban warfare that has paralyzed San Salvador since the FMLN launched its offensive. 

Eleven Lutheran church workers, among them six West Germans, four Americans and one Canadian, were arrested by Treasury police and charged with collaborating with the guerrillas. 

Throughout the day, the thud of bombs or rockets and frightening cracks of artillery and machine guns could be heard in the heart of the city. At night, flares and tracer bullets lit the skies. 

Thousands of people fled their homes in the neighborhoods of Mejicanos, Zacamil and Soyapango in the northern and eastern sections of the city, despite a round-the-clock curfew imposed by the government on those areas. In various sections of those three working-class areas, the rebels were well entrenched and continued to repel government attacks. 

Heavy fighting even occurred during the night underground in the city's sewer system. 

Cristiani said the government was establishing an emergency program to feed the tens of thousands of people who are fleeing their homes to escape the violence. 

The president also said the government has asked the United States to send tear gas to El Salvador that could be used by the armed forces to dislodge guerrillas from houses and apartment buildings. "We will not permit a Beirut-type situation, with the FMLN trying to hold 'liberated' zones" inside the city, he said. 

The United States provides about $500 million in aid annually to El Salvador and has indicated military deliveries will be accelerated. 

Emergency relief workers and ambulance drivers said in interviews that government troops had repeatedly prevented them from evacuating the wounded from areas of the capital where fighting was taking place. The government said it could not guarantee their safety. 

In hospital interviews, several civilian victims of the fighting said they had been confined to their homes by the government curfew when rockets, bombs or large-caliber machine-gun fire hit them. 

Hospitals around the capital reported 1,627 civilians have been injured and more than 100 killed since Saturday. The armed forces reported that 200 soldiers had been killed and 540 injured in the fighting. They said 584 rebels had been killed and 261 injured, but diplomats cautioned that government figures on rebel casualties appeared to be exaggerated. 

The government continued to deny that it was using bombs in residential areas of the city. However, when Vice Foreign Minister Ricardo Valdivieso was asked about allegations of bombings in specific areas of the capital where the rebels are ensconced, he replied, "It was my understanding that civilians had been evacuated from those areas." 

Those killed in the attack on the churchmen, in addition to Ellacuria and Martin-Baro, include: 

Segundo Montes, 56, a Spanish-born sociology professor and Jesuit priest who did extensive work on Salvadoran refugees in the United States. 

Amando Lopez, 53, a Spanish-born philosophy professor and Jesuit priest. 

Joaquin Lopez y Lopez, 71, a Salvadoran-born Jesuit priest who was director of a center for humanitarian assistance affiliated with the university. 

Juan Ramon Moreno, 56, a Spanish-born Jesuit priest who was director of two university-related programs. 

Elba Ramos, 42, a cook, and Celina Ramos, her daughter, 15.