For decades, this city by the bay has lured millions with its panoramic vistas, quaint neighborhoods and wide-open lifestyles. But today this western mecca is shocked by a series of acts of violence unparalleled in recent American history.

In the last 10 days, San Francisco has lost its mayor, a supervisor and a once-powerful activist minister who led virtually his entire congregation into a macabre act of mass self-destruction.

Even more disturbing to many San Franciscans, these deaths appear part of a pervasive atmosphere of terrorism that has enveloped the region since the early 1960s.

Beginning with the 1964 student disturbances at the University of California at Berkeley, the Bay area has been rocked repeatedly by explosive outbursts, perpetrated by a wide variety of groups against a bewildering array of targets. Among the most recent:

On Nov. 6. 1973, Oakland's first black superintendent of schools, Dr. Marcus Foster, was gunned down in a parking lot by two members of the Symbionese Liberation Army (SLA), using cyanide bullets.

On Feb. 4, 1974, eight other SLA members kidnaped a newspaper fortune heiress, Patricia Hearst, from her Berkeley apartment. Four months later six SLA members died in a gun battle with Los Angeles police.

On Sept. 22. 1975, Sara Jane Moore, a recent convert to the revolutionary cause, jumped out of the crowd in front of San Franciso's St. Francis Hotel and fired a shot, narrowly missing then-president Gerald R. Ford.

On Nov. 14, 1976, a bomb was planted and detonated in a window flower box outside the home of San Francisco then-supervisor and now acting Mayor Diane Feinstein.

On Jan. 25, 1977, three shots were fired into the real estate office of San Francisco Supervisor John Barbagelata, less than 12 hours after he received a communique from the terrorist New World Liberation Front (NWLF) threatening him and five other civic leaders with death. Ten days later, a pipe bomb destroyed the car of San Francisco Attorney John Freitas in front of his home, rattling windows 14 blocks away.

On Oct. 23, 1977, a member of Oakland's Black Panther Party was killed in a shootout next to the home of a key witness in the upcoming murder trial of Panther leader Huey P. Newton. The Oakland district attorney branded the incident a planned assassination attempt, and was only the latest in a long series of violent altercations involving the Panthers.

On July, 1978, a pipe bomb attached to a van belonging to California state Sen. Milton Marks' daughter exploded outside their San Francisco home.

Trying to make sense of these events, some here are pointing to the Bay area's long established tradition of tolerance, which, they say they believe, has led to the infusion of a disproportionate number of unstable people into the area.

"A lot of people have come here to find new possibilities that didn't exist back home. All these people come here looking for something," said Dr. Gayle Bates, a prominent San Francisco psychologist long active in the city's politics.

"Out of these are a certain group on the margin, people from whom the lack of structure and limits here creates enormous anxieties. There's nothing here to keep this craziness under control."

In addition to the area's unique cultural mix, there has also been along with it a long tradition of political activism and idealism on both the left and the right. It is a legacy that many among the politically active interviewed today feel has produced immense frustation when high expectations were dashed with the coming of the relatively quiescent post-Watergate era.

"There's nothing to rally people anymore, nopolitical movements, there's nothing to be positive about," said Frederick Ellis, a longtime Bay area activist and a member of a local Democratic county central committee. "So what could people do? They just freak out."

"Look at Dan White, a high school hero, working class, idealistic, my country right or wrong. Everything is good, everything is moral, and then he finds out that the political game doesn't work that way," he said.

Frustrated with their experiences inside the political system, people here continue to be sterwn across the extreme spectrum from the Peoples Temple to paramilitary vigilante groups like the Posse Comitatus.

"You go to the midwest, and there people more or less buy the program, they buy the list of alternatives. Here the people don't," said Ken Meade, a former state assemblyman from Berkeley. "There are a lot of people who have come here for whom the politics practiced in the rest of the country are simply irrelevent."

While Meade, a close friend of the late mayor, and other liberals pledged to continue in the area's tradition of tolerance, there are others here who say it is time to crack down and stop functioning as a haven for the nation's disgruntled extremists.

"We have here some very socially bizarre people," said San Francisco Supervisor Quentin Kopp, a frequent target of threats by underground groups. "What accounts for it is the sympathetic attitude from these people in power. People like Peoples Temple have been used in political campaigns and are apparently effective. In the last few years San Francisco has become a focal place for these people."

Whatever their political point of view, however, most political leaders here share a common fear of the rising tide of violence aimed against their peers. Some, like Oakland state Sen. Nick Petris, a target of a death threat last summer, say they believe politicians have become scapegoats for a public utterly frustrated with the nation's course.

"There's something wrong, and I don't know where," Petris said. "We politicians have become the whipping boys and the targets. It's become very fashionable to take potshots at politicians. People are turned off, it's all pretty dismal."

Whatever the cause, terrorism has become an almost everyday fact of public life in the bay area. In the last seven years there have been some 125 bombings in the region, aimed at local political figures, corporate leaders, the media and exclusive social clubs.

"We're probably the only office in the country outside of New York that has a bomb squad," said one beleagured agent at the FBI's San Francisco office. "We've had two attempts on the life of the president, the Patty Hearst thing, the Chowchilla kidnap, all these prison gangs and now the Peoples Temple and the City Hall shooting. Gee, all we have to deal with back in the East was a simple old Cosa Nostra."

For many bay area residents, particularly those within the troubled political community, the greatest challenge ahead is finding the will to go on, to continue working in a system they say they fear constituents no longer believe in.

"I am very bewildered about what to do now," said Sen. Petris. "I was a real close friend of George (Moscone), but I have to think (about) the long run. We have to work to improve our society, I guess - we just can't run away from it."