Israeli forces entered Bethlehem early Friday, retaliating against the home town of a Palestinian homicide bomber who blew up a Jersusalem bus, killing 11 passengers and wounding dozens.

The first Israeli forces entered the West Bank town from the south, witnesses said, and surrounded the Dheisheh refugee camp next to the town.

Other soldiers headed for the Church of the Nativity, said Israeli military spokesman Doron Spielman. He said the object was to prevent gunmen from seeking refuge in the church.

In April, dozens of gunmen fled into the church ahead of invading Israeli troops, setting off a tense 39-day standoff. It ended when Israel and the Palestinians agreed to send 26 of the gunmen to Gaza and exile 13 others to Europe.

Spielman, who was accompanying the troops, said the goal of the mission was "to change the reality in Bethlehem." He said since the August pullout, Palestinians have set up a "terror infrastructure" and prepared homicide bomb attacks. He said the Palestinian Authority had "failed miserably" in its responsibility to prevent attacks.

Lt. Col. Guy Hasson, a senior commander, said troops imposed a curfew and were searching for 30 Palestinians involved in planning the Thursday homicide bombing and other attacks.

The sudden escalation in Mideast violence was another blow to U.S. and other efforts to keep the Israel-Palestinian conflict at a low ebb while Washington concentrates on its campaign against Iraq.

Prime Minister Ariel Sharon, who met with his defense minister and other officials, decided the army would carry out a "pinpoint operation," Sharon adviser Raanan Gissin said.

Two militant Islamic groups claimed responsibility for Thursday morning's bomb attack: Islamic Jihad and Hamas. Gissin said Hamas would be the group targeted.

Earlier, 13-year-old Hodaya Asaraf who loved to draw was buried at sunset Thursday on a Jerusalem hilltop. Four of the 11 who died in the attack were children: two 13-year-olds, an 8-year-old boy who died along with his grandmother, and a 16-year-old boy whose mother also was killed.

"Her friends said the last thing she drew were leaves," said a teacher, Chena Ben-Yaakov. "The leaf has fallen."

Passengers and police said the bomber boarded bus No. 20 and detonated the explosives belt at about 7:10 a.m., as the bus was stopped in Jerusalem's Kiryat Menachem neighborhood, police said.

The blast blew out the bus windows and sent glass shards and body parts flying. Hours later, a man's arms dangled from a broken bus window and a torso was covered with a blue and white checkered blanket.

Maor Kimche, 15, was among those on the bus, which was jammed with high school students, soldiers and the elderly.

"Suddenly, it was black and smoky. There were people on the floor. Everything was bloody. There was glass everywhere and body parts," Kimche said.

The 10th grader jumped out of a bus window and was scooped up by a taxi driver who took him to Hadassah Hospital, where he was treated for a leg injury.

He said he'd ride buses again. "How else will I get to school?" he asked.

Eleven people were killed and at least 48 wounded, eight of them seriously. Israel Radio said many of the casualties were students, though hospital officials declined to give a breakdown.

Israeli police identified the bomber as Nael Abu Hilail, 23.

Abu Hilail's father, Azmi, said he was pleased with his son. "Our religion says we are proud of him until the day of resurrection," Abu Hilail said. "This is a challenge to the Zionist enemies."

He said Israeli troops had arrested another son and a nephew after the bombing.

Several of Nael Abu Hilail's friends said he was a supporter of Islamic Jihad.

President Bush condemned the bombing, saying the goal of the United States is to see two independent states — Israel and Palestine — living side by side in peace.

U.N. Secretary-General Kofi Annan called the attack "utterly reprehensible" and appealed to Palestinians and Israelis not to be blinded by hate.

Sharon adviser Gissin accused the Palestinian Authority of assisting the attackers and said that with such violence, it seemed futile to bring about a limited truce and withdraw from some Palestinian areas.

"All our efforts to hand over areas .... and all the talk about a possible cease-fire, that was all window dressing because on the ground there was a continuous effort to carry out as many terrorist activities (as possible)," Gissin said.

There was no official comment from the Palestinian Authority, but Ghassan Khatib, the Palestinian labor minister, accused Israel of provoking the attacks with strikes against militants.

The Israeli army has enforced stringent travel restrictions on Palestinians in the past 26 months of fighting, and has reoccupied most West Bank towns in an attempt to stop the attacks. However, Israeli security officials say they continue to receive dozens of warnings every day about planned attacks.

Israel's range of responses is restricted by the possibility of a U.S. strike against Iraq.

Several Israeli hard-line leaders have called for Arafat's expulsion in retaliation for bombings, but such a step is sharply opposed by Washington, which is eager to maintain the support of moderate Arab governments at a time of confrontation with Iraq.

Israel's new Labor Party leader, Amram Mitzna, repeated his pledge that if elected prime minister, he would fight terror, but would also disengage from the Palestinian territories. Mitzna has said he would pull settlers and soldiers out of the Gaza Strip and would restart negotiations with the Palestinians unconditionally.