Associated Press A paramedic carries a wounded man after a suicide bomber blew himself up inside a bus near the Jerusalem neighborhood of Gilo on Tuesday. At least 14 people are reported killed and more than 40 injured, police said.

JERUSALEM ÷ Stymied twice before, a Palestinian attacker was devastatingly successful Tuesday: He detonated a nail-studded bomb in a bus crowded with high school students, killing 19 passengers and himself.

Israel responded by sending tanks into the West Bank town of Jenin, later announcing that it would retake and hold parts of Palestinian territory until attacks against its civilians end.

Several tanks rolled into Jenin and three of them entered the Jenin refugee camp, Palestinian security officials said. The Israeli military had no comment.

Hours after the blast, an angry Prime Minister Ariel Sharon strode past a row of victims in body bags and peered into the bombed-out bus, vowing to retaliate. Two students were among the dead and four were among dozens wounded in the attack, the deadliest in Jerusalem in six years.

The decision to seize parts of the West Bank came with President Bushās planning to make a major Mideast policy address this week. Bush is expected to propose establishing a "provisional" Palestinian state in part of the West Bank and Gaza without deciding on its final borders ÷ and while neither side has embraced the idea, there is some hope that a renewed and forceful U.S. diplomatic drive might help end 21 months of carnage and despair.

An Israeli statement, issued after late-night consultations between Sharon and his top Cabinet ministers, said Israel was changing its response to "murderous acts of terror."

The statement said Israel will capture "Palestinian Authority territory. These areas will be held by Israel as long as terror continues. ... Additional acts of terror will lead to taking of additional areas."

Sharon, surveying the devastation from Tuesdayās attack, questioned Palestinian leader Yasser Arafatās ability to run such a state, saying, "It is interesting to know what kind of Palestinian state they mean."

Although Sharon has made clear he wants Arafat out of power, he apparently isnāt ready to drive him into exile. And the anticipated U.S. initiative makes timing politically difficult for any military offensive.

Israeli political commentator Keren Neubach told Israel TV Sharon considered expelling Arafat, but decided against putting the question to a Cabinet vote because some of his security chiefs oppose such a move.

The prime ministerās office did not immediately return a call for comment.

If Sharon decides against exile, "it will be solely because of the perceived need to work with President Bush and to allow the Bush initiative to succeed," Israeli strategic policy expert Gerald Steinberg said.

However, Palestinian Cabinet and community members were anticipating a response directed at Arafat, and some international organizations ordered their employees to leave Ramallah. Arafatās headquarters in the West Bank town have been under siege off and on since December.

The Palestinian Authority condemned the attack, but the words werenāt expected to affect Israelās response. The Palestinian leadership has not appeared ready to act decisively against radical groups, as Israel has demanded.

In Ramallah, Palestinians anticipating an army invasion and extended curfew began hoarding food.

"The Israeli response usually is against the Palestinian people, the Palestinian president and the Palestinian Authority," said Labor Minister Ghassan Khatib. "It will not be any surprise if they decide to invade Ramallah again or impose a new siege on the president."

In Washington, the White House said Bush condemned the bombing "in the strongest possible terms," but aides wouldnāt say if it would delay his policy statement, expected Wednesday.

Bush has been formulating his approach to Mideast peace for weeks, during which he has met with Sharon, Egyptian President Hosni Mubarak, Saudi Crown Prince Abdullah and senior Palestinian officials.

After the suicide bombing, Israel appeared to be letting Arab leaders know Arafat was running out of chances ÷ and that an Arab failure to speak strongly against such attacks could provoke Israeli action.

Israeli Defense Minister Binyamin Ben-Eliezer spoke with Osama el-Baz, a top adviser to Mubarak, and Jordanian Prime Minister Ali Abul-Ragheb to "inform them of the grave situation in Israel following the recent terror attacks," according to a Defense Ministry statement.

Ben-Eliezer emphasized the Israeli governmentās obligation to protect its citizens and sought "a determined consolidation by the Arab world against the policy of terror and violence."

Israeli Foreign Minister Shimon Peres cut short a visit to eastern Europe to return home after Tuesdayās bombing.

The nail-studded bomb tore through the bus as it waited at a crowded intersection just before 8 a.m., sending bodies flying through windows and peeling off the roof and sides.

The Islamic fundamentalist group Hamas identified the assailant as Mohammed al-Ghoul, 22, a graduate student in Islamic studies from the Al Faraa refugee camp in the West Bank. Al-Ghoul left behind a farewell note in which he said heād tried twice before to stage attacks.

"This time, I hope I will be able to do it," he wrote. "How beautiful it is to make my bomb shrapnel kill the enemy."

Inside a religious school a few hundred yards from the blast, 15-year-old Shmuel Calfon was praying with other students when they heard the explosion.

"Everyone looked at each other and thought, āThat was an attack.ā But I didnāt want to be the one to say it," Calfon said. Soon, sirens wailed and students began shouting and calling home to assure worried parents.

Police had been on high alert since Monday after receiving warnings that suicide bombers were trying to carry out an attack in Jerusalem.

After 70 suicide bombings in 21 months, handling the blasts has become a tragic routine: ambulance sirens wail as they rush to the scene, survivors call home and victims are taken to hospitals or their remains collected.

"Iāve seen so many attacks, I didnāt get excited," said Eliran Ben-David, a 17-year-old student at the Ort Spanian school 150 yards from the bomb site. Ben-David was near a bombing in Jerusalem last December.

But school administrators said outward bravado was only masking turmoil fed by fear of attacks. "A kid who says, āIām calmā is really saying āIām in controlā. Heās not calm," said district schools supervisor Ruth Meir.