The Israeli army continued to increase its military offensive in the West Bank early Tuesday, rolling tanks into Bethlehem after attacking a Palestinian security headquarters near Ramallah.

Tanks entered Bethlehem from two directions, witnesses said, heading toward the center of town, where the Church of the Nativity marks the traditional birthplace of Jesus. Witnesses heard exchanges of gunfire a few hundred yards from the church.

The Israeli military said forces took up controlling positions in the town and were searching for suspected terrorists and weapons. A statement said Israeli forces also searched three Palestinian villages in the northern West Bank.

Earlier, the Israelis attacked the headquarters of Palestinian Preventive Security outside Ramallah, firing tank shells and machine guns, Palestinian officials said. Israeli helicopters also fired at the building, they said, engulfing it in flames and causing many casualties. West Bank security chief Jibril Rajoub had given orders to the 400 men inside to resist. "Of course, I could not give a different order," he said.

After daybreak, the flames had ebbed, leaving two of the buildings in the compound smoldering, blackened wrecks, one with a shattered roof. Holes were visible in the walls of several other buildings in the compound.

Palestinian officials said that Israeli soldiers used 60 Palestinian civilians as human shields in front of the tanks before the assault. Army spokesman Olivier Rafowicz "categorically denied" the charges. Israel banned reporters from the scene, and there was no independent confirmation.

The battle wound down just before daybreak, Palestinian officials said. In a statement, the Israeli military said many "leaders responsible for the recent wave of terrorism" were holed up in the building and had ignored an ultimatum to surrender.

Rajoub, who was not at the compound, told Israel Radio, "The situation is very, very, very difficult." He denied that terrorist suspects were in the building.

Israeli leaders said the widening assaults were meant to destroy the Palestinian terrorist infrastructure. Palestinians, however, said the military movements were a campaign of terror against civilians.

For the first time, a senior Israeli official gave a timeframe for the military operation. Foreign Minister Shimon Peres told MSNBC, "We are in the territories for three or four weeks. We don't intend to occupy the places."

Peres added that Israel does not intend to dismantle the Palestinian Authority or harm Palestinian leader Yasser Arafat.

Since the latest Israeli offensive began Friday with an assault on Arafat's compound in Ramallah, Israeli forces have arrested about 700 suspected militants, said military spokesman Brig. Gen. Ron Kitrey.

On Monday, Israeli troops backed by armor pounded a Ramallah building with anti-aircraft guns, briefly pushing into Bethlehem and sending the deafening echo of tank shells through Palestinian streets.

Later Monday, Palestinians opened fire on an Israeli car in the West Bank, wounding three members of a family. Israeli soldiers fired back, killing one of the gunmen, the military said.

On another front, Hezbollah guerrillas in Lebanon fired two rockets at Israel, the military said. The rockets exploded harmlessly in fields. Sheik Hassan Nasrallah, leader of the Lebanese Hezbollah guerrillas, has called for helping the Palestinians in their struggle against Israel.

Troops searching for Palestinian militants and weapons caches carried out house-to-house searches and engaged in running battles with gunmen. In the center of Ramallah, soldiers used vehicle-mounted anti-aircraft guns to pulverize the facade of a building where Palestinian gunmen were holed up, sending chunks of masonry plunging into the street.

Israeli forces also moved into the northern Palestinian towns of Qalqilya and Tulkarem on Sunday night and Monday.

As Israeli forces advanced, Palestinian militants were killing Palestinians suspected of collaborating with Israel. Ten bodies were found in the West Bank, including seven taken by militants from a temporary jail and shot in the streets of Tulkarem.

In the sixth Palestinian attack in six days, a car bomb exploded near downtown Jerusalem, killing the driver and a policeman. Police said the policeman stopped the car and the driver, a Palestinian, set off the bomb. Al Aqsa Martyrs Brigade, a militia linked to Arafat's Fatah movement, claimed responsibility.

Sporadic gunfire rang out after dark in Ramallah, a few miles to the north, where a tight curfew and continued fighting have turned a busy commercial center into a ghost town. The boom of tank shells was heard after night fell. Eight Israeli soldiers were injured — two seriously — in Ramallah and another in Qalqilya, a military source said. The bodies of two Palestinian police were found in a park in the city's center, Palestinian military intelligence said.

Among the fugitives being hotly pursued by Israeli forces in Ramallah was Palestinian militia leader Marwan Barghouti, a senior Israeli security source said, speaking on condition of anonymity. Israeli officials have said Barghouti was involved in numerous deadly attacks on civilians.

President Bush called on Arafat to put a stop to anti-Israeli attacks. "There will never be peace so long as there is terror, and all of us must fight terror," Bush said.

Israeli soldiers set up more barricades in Ramallah's streets, turning cars already smashed by tanks onto their sides to form roadblocks. Pressing ahead with searches, Israeli soldiers broke down the doors of homes in Ramallah and Qalqilya, Palestinians said.

"They smashed pictures that were on the wall and looked everywhere, emptying closets and throwing around our clothes," said 26-year-old Nafiza Rouf, who said soldiers spent about two hours in her Ramallah house. Her 24-year-old brother Niad was made to kneel motionless while soldiers shouted questions and abuse at him, the family said.

An 11-year-old Palestinian boy was killed by gunfire from Israeli soldiers as he played near a market in Rafah, in the Gaza Strip, Palestinian hospital officials said.

In Ramallah, nearly all the dead over the course of the incursion — at least 25, by Palestinian count — have been men in their 20s and 30s. At Ramallah Hospital, the city's main medical center, doctors pulled open the metal doors of the morgue to display bloodied bodies of the young men, wrapped in sheets, and said they had not been allowed to transport them out for burial.

Tanks had entered Bethlehem before dawn Monday and an Israeli soldier was shot and killed by a Palestinian sniper, the military said. The troops also moved into the nearby villages of Al Khader and Beit Jall. The tanks pulled back to the edge of Bethlehem during the course of the day before moving back in early Tuesday.

In an earlier major incursion, Israeli troops and tanks moved into Bethlehem in mid-March. Soldiers went through the adjacent Aida refugee camp, pounding holes in the walls of houses to get from one to the other, searching for suspects and weapons caches.

In Beit Jalla, Israeli forces imposed a curfew and occupied buildings overlooking Bethlehem.

Six foreigners protesting the Israeli invasion were injured when they marched up to tanks in Beit Jalla, said doctors. One woman was hit in the stomach by a bullet, and witnesses said the others were struck by shrapnel after an Israeli soldier fired into the ground. An Associated Press Television News cameramen, Iyad Hamad, was also lightly injured. The military would not immediately comment on the incident.

State Department spokesman Philip Reeker criticized Israel for injuring the protesters and said the military should investigate the incident to prevent such incidents in the future.

Palestinian Cabinet Minister Saeb Erekat accused Bush and the United Nations of ignoring the Palestinians' suffering. "There is total destruction, total state terror against the Palestinians," Erekat told The Associated Press.

The Associated Press contributed to this report.