JERUSALEM, NOV. 10 -- A 17-year-old Palestinian schoolgirl was shot to death today by Jewish settlers outside her high school during a rock-throwing demonstration in the occupied Gaza Strip, according to an Israeli Army spokesman and witnesses.

It was the latest in a series of recent incidents in which Israeli soldiers or settlers have killed Palestinian demonstrators or bystanders in Gaza or the West Bank. At least 18 Palestinians have been killed this year -- during demonstrations or, in one case a month ago, a shootout with Israeli security forces. Several Israeli civilians have also been killed by Arabs in the occupied territories.

Under Israeli military law, Jewish settlers are entitled to carry arms but are supposed to use them only if their lives are endangered. The Army has rejected settler requests to form a Jewish civil guard in Gaza, but some residents, claiming they are regularly pelted by Arab youths on the main roadways, have vowed retribution.

The Army said residents from the Gaza settlement of Gush Qatif were traveling in a minibus on the main road to Tel Aviv past the Deir Balah refugee camp when their vehicle was hit by rocks from a girls' high school.

One of the settlers, who was not identified, told Army radio that the route was blocked by a barricade and that the bus was stoned by about 50 girls as it attempted to drive around the obstruction. "We got out immediately and shot in the air," said the man. "More than that, we do not know."

One girl, identified by residents as Intissar Atar, 17, was hit during the firing and pronounced dead on arrival at nearby Shifa hospital.

Six settlers were detained for questioning, according to the radio. While Arab residents are subject to military occupation laws, the settlers are under Israeli civilian authority and may be tried in civilian courts in Israel.

After word of the girl's death reached Gaza City, about 10 miles away, a protest occurred outside the gates of the Islamic University of Gaza. A large contingent of soldiers surrounded the area, firing tear gas and, in one instance, live ammunition, according to witnesses. They said one student was injured by gunfire and another by a tear-gas canister.

Gen. Yitzhak Mordechai, military commander of the area, paid a condolence call to the parents of the dead girl and pledged to "take all the necessary steps so that this tragic incident will not escalate."

The Palestine Press Service, a media information outlet sympathetic to the outlawed Palestine Liberation Organization, reported that the demonstration outside the high school was to protest Jordanian King Hussein's treatment of PLO leader Yasser Arafat at the Arab summit conference in Amman. The girls waved PLO flags and posters of Arafat, the press service said.

About 2,000 Jews live in settlements that occupy 30 percent of the Gaza Strip. It is also home to 650,000 Palestinians, many of them living in urbanized refugee camps that are said to be among of the most densely populated areas in the world.