Israeli soldiers stormed the fortress-like Palestinian headquarters in the city of Hebron early Tuesday, occupying the seventh of eight main West Bank centers. Palestinian security officials said four policemen were killed.

The violence came as Israeli and Palestinian leaders expressed widely divergent views on a Mideast policy speech delivered Monday by U.S. President George Bush. He called for a new Palestinian leadership and an end to terrorism, holding out the prospect of a provisional Palestinian state.

Israeli troops surrounded the hilltop compound, exchanging fire with police, and then soldiers entered the building and searched from room to room, Palestinians said, while forces outside used loudspeakers to demand that all the Palestinians inside surrender with their hands raised.

Security officials said that the Palestinian security chief, Nizam Jaabri, and about 20 others had turned themselves in. Palestinians said some are suspected of killing five people thought to be collaborators with Israeli intelligence.

The Israeli military said soldiers entered Hebron to operate against the "terrorist infrastructure" there. A military statement said a "large number" of suspects had been arrested. Also, soldiers discovered an explosives laboratory.

Soldiers declared a curfew in the city, confining more than 100,000 Palestinians to their homes, residents said.

The large, old building served the British army when they controlled the area until 1948. Then the Jordanian army took over, and when Israel captured the West Bank in 1967, the Israeli army had its headquarters there.

When Israel turned most of Hebron over to the Palestinians in 1997, the Palestinians converted the structure into an office for the regional governor and security forces.

The 1997 accord left Israel in control of about 20 percent of the city, guarding three enclaves where Jewish settlers live in the center of Hebron.

Also, soldiers arrested 11 Palestinians in the village of Beit Fajjar, near Bethlehem, the military said Tuesday.

Israeli forces hold seven West Bank Palestinian towns in a tight grip, following a decision to move into Palestinian areas in retaliation for bomb attacks. At least 700,000 Palestinians were confined to their homes by army curfews, and Israeli tanks encircled Palestinian leader Yasser Arafat's headquarters compound in Ramallah. In Nablus, city Gov. Nahmoud Alol said Israeli troops entered his six-story apartment building, evacuated two floors and locked the rest of the residents inside their apartments.

Only Jericho, isolated in the Jordan Valley, was free of Israeli troops.

Reacting to Bush's speech, Arafat issued a statement calling it a "serious effort to push the peace process forward."

However, other Palestinians were hard-pressed to find anything positive. Palestinian Cabinet Minister Saeb Erekat said Bush's call for a new leadership was "not acceptable." Palestinian Cabinet Secretary Ahmed Abdel Rahman said that Bush "mixed up" the concepts of terrorism and resistance to Israeli occupation.

Israelis were pleased with the speech, but joined the Palestinians in expressing doubts about the concept of a provisional Palestinian state, an idea neither side appeared to understand.

Prime Minister Ariel Sharon's spokesman, Raanan Gissin, welcomed Bush's call for a new Palestinian leadership "not compromised by terror." Gissin said, "When they chose Arafat, they chose a strategy of terror, and they chose to continue sending suicide and homicide bombers to Israel."

At the Karni crossing between Israel and Gaza early Tuesday, Israeli soldiers shot and killed a Palestinian who was throwing grenades, the military said.

In Gaza on Monday, an Israeli helicopter fired three missiles at a car in Rafah, a town on the border with Egypt, where there are frequent clashes between Palestinians and Israeli forces. The car was turned into a smoking, twisted wreck.

The Israeli military said the target was Yasser Rizik, the Rafah commander of the Hamas military wing, who died instantly. Five others were killed, including four Hamas activists, the group said.

Speaking in Israel's parliament, Sharon announced, "We are preparing massive activity against Hamas in the (Gaza) Strip," and pointed to the helicopter strike as the first chapter.

Hamas leaders threatened revenge against Israel. "We emphasize our right to continue the jihad (holy war) and resistance, and to intensify the martyrdom operations," Hamas said in a statement. "Martyrdom operations" is the term Hamas uses for homicide bomb attacks.