A right-wing Jewish extremist shot and killed Prime Minister Yitzhak Rabin tonight as he departed a peace rally attended by more than 100,000 in Tel Aviv, throwing Israel's government and the Middle East peace process into turmoil.

The lone gunman met Rabin, 73, as he walked to his car in the Kings of Israel Square in front of Tel Aviv's city hall. The prime minister had just stepped off a massive sound stage where he had linked hands with fellow ministers to sing "The Song of Peace." Identified by police as Yigal Amir, a 27-year-old law student, the assassin fired three shots into Rabin's back at close range.

A cordon of security officers bundled the gunman away as Rabin was rushed by ambulance to Ichilov Hospital, just a few blocks away in the heart of Tel Aviv. He arrived there with no pulse and no blood pressure, according to Health Minister Ephraim Sneh, and died on the operating table at 11:10 p.m. (4:10 p.m. EST), an hour and a quarter after being shot. Seven minutes later, shouting over the sobs and gasps of policemen and journalists, Rabin's senior aide, Eitan Haber, announced his death.

Amir, who studied law and computer science at Bar Ilan University, was among the founders of an illegal Jewish settlement called Maale Yisrael that was built this summer in defiance of the then-impending deal to extend Palestinian self-rule to much of the West Bank. Israel Radio and television reported that he spoke calmly to police tonight, telling them he acted alone, planned the assassination with a sound mind and had no regret.

Under Israeli law, Foreign Minister Shimon Peres becomes acting prime minister but the government is deemed to have fallen. That means it is up to President Ezer Weizman, a political maverick, to select a party leader to attempt to form a new governing coalition. The choice boils down to Peres or Binyamin Netanyahu, leader of the opposition Likud Party. At a 2 a.m. news conference, Weizman declined to discuss his next move. "The man has not yet been buried," he said. Rabin's funeral is scheduled for Monday.

Rabin's death is likely to advance elections that already were shaping up as a decisive test of the government's historic movement toward peace with its Arab neighbors, the Palestine Liberation Organization above all. The Israeli public is profoundly divided, and Rabin's Labor Party-led parliamentary coalition -- dependent on opposition defectors and back-room deal-makers loyal only to Rabin -- has hung on until now by a thread.

In no case can elections be later than scheduled, a year from now, and under many scenarios they will come sooner.

There had been no political assassination since Israel's founding in 1948. Tonight, the country reeled.

"This is a great, tragic moment in Israel's modern history," said Yaron Ezrahi, a political scientist at Hebrew University. "There's no question it will have profound effects on Israeli politics, the peace process and the government well beyond the next election. This is an event whose reverberations are so large that it is hard to assess it at this moment."

Many commentators, from right to left, have expressed alarm since summer at the increasingly violent cast of Israeli street politics. Jewish demonstrators have repeatedly blocked roads, set fires and clashed with police in protests against what they have called a "junta" and a government of "traitors" and "murderers."

Tonight's Tel Aviv demonstration was aimed at countering the past months' rallies of the right, in numbers and tone. Organizers, including the Labor and Meretz parties and the advocacy group Peace Now, brought the largest turnout in memory to the Kings of Israel Square -- a traditional site for national political demonstrations -- and deliberately chose a light-spirited tone.

The slogan of the night was "Yes to peace, no to violence." But an upbeat, carnival atmosphere prevailed, with popular singers such as Ahinoam Nini providing entertainment, and even Rabin and Peres joining in song.

Miri Aloni, a liberal activist, sang her signature number, "The Song of Peace," and passed the microphone to Rabin and Peres as they linked arms and swayed on the stage.

"Just sing a song of peace, don't whisper a prayer, sing a song of peace loudly," went the refrain.

Peres, alluding to the government's uncertain musical talents, drew a big laugh from the crowd by quipping: "We know how to make peace. We don't know how to sing. But in the making of peace we won't be off-key."

Later, his head bowed and voice breaking with emotion, Rabin's lifelong Labor Party rival said the prime minister had folded the song's lyrics and placed them in a breast pocket before descending from the stage.

"The bullets ripped them apart," Peres said.

Rabin's speech to the rally, his last, was confident and brief.

"I was a military man for 27 years," said the former army chief of staff, who was Israel's youngest brigade commander in the 1948 war of independence. "I fought as long as there was no chance for peace. I believe now that there is a chance for peace, a great chance, and we must take advantage of it."

Moments before descending from the stage, Rabin gave a final radio interview.

"I always believed that most of the people are against the violence that lately has taken a form that harms the basic system of Israeli democratic values," he said. "And they support peace. People have doubts about their personal security, but they do not have doubts that the path of peace should be pursued. I think this rally gave voice to many of the people."

A few minutes later, the program ended with the singing of "Hatikva," the Israeli national anthem. At 9:55 p.m., with many demonstrators still dancing in the square to a live concert by rock star Aviv Geffen, the three shots rang out.

Before tonight, there had been some recent disturbing signs of willingness to translate the anti-government rhetoric of Jewish protesters into anti-government violence.

Environment Minister Yossi Sarid, traveling in his government sedan, was run off the main Jerusalem-Tel Aviv highway by a West Bank settler in an adjacent car who recognized the left-wing cabinet official and swerved his car repeatedly into Sarid's.

Then, a month ago, right-wing demonstrators attacked the car of Housing Minister Binyamin Ben Eliezer as he arrived to cast his ballot on a vote of confidence in the government. They damaged the car and nearly upended it, according to Eliezer's account at the time. The government narrowly survived the parliamentary vote, 61 to 59.

That same night, a right-wing extremist leader was photographed holding a Cadillac emblem that had been torn from Rabin's official sedan in a similar attack. Although Rabin was not in his car at the time, some extremists said they had proved they could penetrate his security, and would do so again.

Also that night, tens of thousands of right-wing demonstrators massed in Jerusalem under the slogan that "the people did not sign" the Sept. 28 West Bank peace accord with PLO leader Yasser Arafat, an effort to remove legitimacy from Rabin's government. The rally featured speeches by Netanyahu and other Likud leaders.

A larger-than-life effigy of Rabin, dressed in the uniform of the Nazi SS, stood out that night from a sea of anti-government placards. Netanyahu, who later criticized the effigy, did not do so during the rally and delivered his speech as planned.

Environment Minister Sarid, who described Rabin tonight as "the most important statesman of this time, maybe in the whole world," blamed the mainstream Israeli right for creating the climate of his assassination.

"He fell victim to a lot of incitement and hatred and hostility," Sarid said. "For a long time we said that this is giving legitimacy to murder. But our admonitions went unheard, and there was encouragement, and the blood was spilled. One man did it, but there were many more inciters."

Until tonight, Netanyahu has walked a careful balance, distancing himself from violence but holding Rabin and his policies chiefly responsible for creating the public rift that made it possible.

Netanyahu declined to take questions tonight, but in a statement to Israel Radio expressed "deep mourning and severe shock."

"We must vomit from our society anyone who infringes the most basic rule of human society, Thou shalt not kill,' " he said. "I pray that we learn to maintain restraint and unity in the face of one of the most difficult tragedies that has befallen us since the beginning of the state."

Ori Orr, a fellow former general and key ally of Rabin in parliament, told Israel Television tonight that "None of us can digest this:

"He died in the most important battle he fought, at the hands of evil Jews. Today there is nothing we can do. We can only cry." CAPTION: Yitzhak Rabin addresses Tel Aviv rally at which he was later shot. CAPTION: Israelis light candles in memory of Prime Minister Yitzhak Rabin last night at the spot where he was assassinated after a peace rally in Tel Aviv's Kings of Israel Square.