JERUSALEM, FEB. 26 -- In one of the worst days of violence since uprisings began in Israel's occupied territories, four Palestinians died in protests today as Secretary of State George P. Shultz held his first full day of meetings with Israeli leaders on reviving the dormant Middle East peace process.

Obeying calls by the outlawed Palestine Liberation Organization, leading Palestinian moderates boycotted a planned meeting with Shultz in Arab East Jerusalem. The secretary responded to the snub by urging Palestinians to become "active participants in the negotiations to determine their future." He assured them that the United States is pressing for "positive and rapid change."

Earlier, Shultz held separate two-hour sessions with Prime Minister Yitzhak Shamir and Foreign Minister Shimon Peres and lunched with Defense Minister Yitzhak Rabin. It was impossible to determine whether Shultz made any progress in his bid to gain Shamir's support for what Shultz has called the U.S. "package" of proposals he has brought here.

Shamir said he had "a very friendly and thorough discussion" of the U.S. plan and that he hoped by the time Shultz leaves here Tuesday, "we will have some positive outcome." The prime minister's aides made it clear later that Shamir had not changed in his opposition to several key aspects of the American proposals.

Today's death toll, the highest in several weeks, followed calls from the PLO and other nationalist factions for demonstrations on the Moslem Sabbath against the Shultz mission. Thousands of people returning from morning and noon prayers in the occupied West Bank and Gaza Strip protested by marching, chanting Palestinian slogans and pelting soldiers with rocks and bottles.

One of those killed was a 12-year-old boy shot by soldiers in Jabaliya, the Gaza Strip's largest and most densely populated refugee camp. The Army said the shooting occurred outside the camp's main mosque. A woman in Jabaliya was injured by a gunshot, and officials at Gaza City's Shifa Hospital said about 20 people were treated for injuries from tear gas inhalation or beatings.

In the West Bank village of Toubas, near Nablus, a 55-year-old woman bled to death from a gunshot wound to the right thigh, according to doctors at Ittihad Hospital.

An Army spokesman said the incident began when hundreds of angry protesters attacked soldiers after pouring out of the local mosque. One man threw a knife at an Army officer, who then fired at the man but missed, killing the woman, who was standing behind the assailant.

The other two victims died in unclear circumstances. A man died during violent clashes in the southern West Bank city of Hebron, and doctors said he was killed by tear gas inhalation. The military spokesman said he was "not killed by Army gunfire."

The other was a man brought to a Bethlehem hospital from the nearby refugee camp of Aroub. In both cases the Army said it was investigating the cause of death.

Meanwhile, the Army announced that it has arrested four soldiers for their alleged involvement in beating and breaking the arms of two Palestinians and has suspended their commanding officer. The incident was filmed by a CBS camera crew just south of Nablus yesterday and was viewed by senior Army commanders today.

The film showed three soldiers systematically assaulting two bound men who had allegedly thrown stones at a military patrol. Eventually the soldiers extended the arms of each man and broke them in several places with rocks. The CBS crew said the entire incident took about 40 minutes.

"I was shocked because what I saw on the tape is completely against all orders and instructions on how to behave," said the commander in charge of the north-central region of the West Bank, identified by the Army as Brig. Gen. Zeev, in a telephone interview. If found guilty, he said, the soldiers "will be punished very heavily." He said the two injured men had been released from custody.

Zeev said the soldiers were part of a unit that had served in the Nablus area for two months. He said "coping with this very complicated situation for such a long time" had probably led to the incident.

The Army closed off several population centers to press coverage today. In Nablus, soldiers ordered journalists to leave the main road even though no demonstrations were occurring and other vehicles were allowed to pass. "Last Friday there were more cameras than demonstrators, and we didn't want this to happen again," said a spokesman.

Shultz made a special trip tonight to the American Colony Hotel in Arab East Jerusalem for what he hoped would be a meeting with some of the 15 Palestinians to whom the U.S. Consulate had issued invitations. The Palestinians had first agreed to meet with Shultz but bowed to pressure from the PLO and local activists who insisted that Shultz meet outside Israel with a PLO-approved delegation including Palestinians in exile as well as from the occupied lands.

Speaking in the hotel courtyard, in a garden of orange trees and with the sound of muezzins chanting the call to prayer in the background, Shultz said he had hoped to hear first-hand from the Palestinians "about your aspirations and your point of view.

"Palestinians must achieve control over political and economic decisions that affect their own lives," Shultz said.

"Palestinians must be active participants in negotiations to determine their future. Legitimate Palestinian rights can be achieved in a manner which protects Israeli security," he added.

Shultz met alone with Shamir, who has expressed the deepest reservations about the new U.S. peace initiative. It calls for an accelerated timetable for limited autonomy for Palestinians in the West Bank and Gaza and the start of negotiations on their final status by the end of this year.

An Israeli official close to Shamir said the prime minister had "rejected nothing" but had "made clear his positions." Shamir repeatedly has expressed opposition to accelerating the timetable for autonomy.