A Palestinian killed 11 people and injured at least 49 when he blew himself up on a crowded bus in Jerusalem Thursday in the first resistance bombing in Israel since the start of a general election campaign.The explosion ripped through a bus packed with commuters and school children during the morning rush hour. Witnesses said they had heard children who had been on their way to school screaming "Mamma, Mamma" from the wreckage.

The bombing, the first in Jerusalem since June, provided further evidence that Palestinian resistance men were determined to make their presence felt in the run-up to Israel's January 28 ballot, and raised the specter of harsh military retaliation.

"Suddenly there was a huge explosion, something fell on my head and I fell to the floor," said Yitzhak Cohen, a middle-aged passenger on the bus. "Around me there were bodies everywhere, some of them lying one on top of the other."

A witness identified as Tomer who was driving past the bus when it exploded told Israel radio: "I saw people draped out of windows. Two or three children were screaming inside the bus and then they climbed out."

Passers-by raced to help the victims, many of them burned, bloodied and sobbing. Residents of the Kiryat Menahem neighborhood where the bombing occurred rushed from their houses desperate to learn the fate of their children.

Books spilled out of a black school bag collected by rescue workers and a piece of burned notebook paper fluttered to the ground. The charred torso of one of the victims hung out of a bus window.

CONDEMNATION FROM BUSH AND BLAIR

Meeting on the sidelines of a NATO summit in Prague, President Bush and British Prime Minister Tony Blair condemned the bombing.

"It is clear that those who want to use terror to stop any process for peace are still active. In order to achieve peace all countries in the region must take responsibility, do their best to fight off terror," Bush told reporters.

The latest violence, including Israeli occupation army raids, threatened to undermine U.S. efforts to achieve calm in the region while it seeks Arab support for a possible war on Iraq.

Police said the bomber -- identified by police as man in his 20s from Bethlehem -- was sitting at the front of Bus Number 20 and detonated his explosives as it approached a bus stop.

The bomber killed himself and 11 others, including a 14-year-old girl. Hospital officials said at least half the 49 wounded were under the age of 18.

The bombing was the first in Israel since Prime Minister Ariel Sharon called a snap election after his broad coalition government collapsed earlier this month, setting the stage for voters to make a clear choice between hawks and doves.

Opinion polls show Sharon's Likud party, boosted by the Israeli public's turn to the right amid a surge of bombings during a two-year-old Palestinian uprising for independence, widely favored to defeat the center-left Labor Party.

In deciding his response, Sharon faces the added complication of a Likud vote next week to decide whether he or his more hawkish challenger, former premier Benjamin Netanyahu , will lead the party in the election. Polls have tipped Sharon as the almost certain winner.

Sharon responded to bombings in Jerusalem last summer by sending occupation troops to reoccupy much of the West Bank.

The military wing of the resistance Islamic movement Hamas claimed responsibility for the attack, Hizbollah's al-Manar television said.

"The person who carried out the Jerusalem martyrdom operation is Na'il Azmi Abu al-Hal of the (Izz el-Deen) al-Qassam Brigades," al-Manar said, giving no further details.

Yasser Arafat's palestinian Authority  condemned the bombing but said Sharon was responsible for continued violence because of Israel's occupation army crackdown on Palestinian areas.

Ismael Abu Shanab, a senior official in Gaza for the resistance Islamic group Hamas, said Israel was "paying the price" for its occupation and killing of Palestinian civilians.

ELECTION CAMPAIGN TARGETED

Resistance men have struck during previous election campaigns and have made clear they will do so again despite the view such assaults bolster support for Sharon and hurt his dovish Labor Party challenger Amram Mitzner, who has vowed to reopen peace talks.

Hamas and Islamic Jihad, both dedicated to Israel's destruction, say they see no difference between Israel's parties and will not let up on their bombing campaigns until Israel ends its occupation of the West Bank and Gaza Strip .

Earlier Thursday, Israeli tanks and armored vehicles backed by helicopter gunships rumbled into the southern Gaza Strip and blew up the home of a senior Palestinian resistance man before withdrawing. Hospital officials said three Palestinians were hurt in the area.

Israel launched the raid near the town of Khan Younis after its housing minister told Washington that work on a Middle East peace plan should wait until after January's election, further dimming hopes for ending two years of violence.

At least 1,674 Palestinians and 640 Israelis have been killed since the uprising erupted in September 2000.

PHOTO CAPTION

The covered bodies of victims of a Palestinian resistance bomb attack are lined at the side of the road in Jerusalem Nov. 21, 2002. A Palestinian resistance bomber killed at least 10 other people when he blew himself up on a crowded commuter bus during the Thursday morning rush hour in Jerusalem, police and rescue workers said. (Gil Cohen Magen/Reuters)