Jerusalem ? A Palestinian suicide bomber detonated a powerful explosive Saturday among ultra-Orthodox Jewish worshippers as they poured into the streets after sundown prayers at the end of the Sabbath. At least nine people, including several children, were killed, and more than 30 wounded.

Early today, Israeli helicopters fired four missiles at Palestinian Authority headquarters and a small factory in Bethlehem. The Israeli military said the strike was retaliation for the Jerusalem bombing.

Also Israeli Radio reported that seven Israelis were killed and four injured in a shooting ambush by Palestinians early today in the West Bank.

The thunderous blast from the suicide bombing shook downtown Jerusalem and sent flames leaping into the air from a car that caught fire. Blood splattered the stone wall in front of the Mahane Israel seminary, where up to 1,000 Jews meet every Saturday evening.

The bomber entered the Mea Shearim neighborhood in west Jerusalem, “approached a group of people (and detonated) a large explosive on his body,” said Jerusalem Police Chief Mickey Levy.

Besides the bomber, nine people were killed, including a 1-year-old child and several other children, police said.

“This has nothing to do with warfare, this has nothing to do with national liberation, this has to do with the murder of innocent Jews,” said government spokesman Dore Gold. “The state of Israel knows how to defend the people of Israel, and will do so.”

Palestinian militants had vowed to attack after Israel’s military stormed into two West Bank refugee camps during the past three days. At least 23 Palestinians  including gunmen, policemen and civilians  have been killed in the camps since Thursday, as Israeli troops spent three days searching for militants and weapons in the Balata refugee camp on the edge of Nablus in the West Bank. They pulled out before daybreak today, the military said.

Palestinian security sources said the Jerusalem bomber was Mohammed Daragmeh, 20, a member of the Al Aqsa Martyrs Brigades, which is part of Palestinian leader Yasser Arafat’s Fatah movement. The sources said he came from the Dheisheh refugee camp near Bethlehem.

At the entrance to Dheisheh camp, hundreds of Palestinians staged an impromptu celebration, chanting, “revenge, revenge,” and firing guns into the air.

Arafat’s administration denounced the suicide bombing. But it also criticized Israeli Prime Minister Ariel Sharon for the “crimes against Palestinian civilians” in the refugee camps and called his government “responsible for the deterioration in the region, and any coming deterioration.”