HEBRON, West Bank - Israel's army re-entered this divided city yesterday in the first stage of what officials warned would be forceful retaliation for an ambush by Palestinian gunmen Friday who killed 12 Israeli soldiers and police.

By last night, soldiers had detained 43 Palestinians, blindfolded them and taken them away for questioning as dozens of armored personnel carriers massed on the city's outskirts. Three Palestinian gunmen also were killed in the gunbattle Friday night, and 15 Israelis were injured, four of them seriously.

Army commanders said yesterday that the gunmen targeted soldiers rather than the civilians the soldiers had guarded during Sabbath prayers in the city, where relations between Palestinians and Jewish settlers are perhaps at their worst and where the history of killings is the bloodiest.

Israelis involved in the fighting said panic-stricken soldiers and police had been lured into an alley where they became trapped by cross-fire. Paramedics entered the area while the firing was under way to reach the dead and wounded and dragged people out by their feet. They pushed the bodies to one side and put the injured into armored ambulances that brought them out of the alley one at a time.

The dead in the three-hour gunbattle included Col. Dror Weinberg, 38, commander of the Hebron Brigade, the highest-ranking Israeli officer to be killed during the two-year Palestinian conflict.

"It was hell," said Jonathan Stein, 19, a resident of the nearby settlement, Kiryat Arba, and one of the worshipers. He had reached the settlement's gate after the prayers when he heard shooting and returned with his assault rifle to help. "It was hard to see the blood and the dead bodies."

Israel's Cabinet was scheduled to discuss further responses today, and Prime Minister Ariel Sharon is under increasing pressure from the right to exile Palestinian leader Yasser Arafat, whom officials blame for failing to crack down on militants.

"The question of expelling Arafat is being examined almost hourly," Dov Weissglass, an aide to Sharon, told Israeli Radio yesterday. But Weissglass suggested the timing for such a move is not right because of strong objections from the United States.

Several hundred residents of Kiryat Arba staged a protest last night at the shooting scene to demand that the Israeli army permanently reoccupy Hebron and demolish the Palestinian neighborhood next to their settlement. Police said they restrained many from attacking their Palestinian neighbors.

About 6,000 Jewish settlers live in Kiryat Arba. And 450 settlers live in adjacent Hebron surrounded by 130,000 Palestinians. The city is divided into enclaves controlled by the Palestinian Authority and by Israel, and Palestinians and Israelis share a religious shrine, the Tomb of the Patriarchs, revered as the burial place of the biblical figures Abraham, Jacob and Isaac.

Every Friday evening at the start of the Jewish Sabbath, worshipers from Kiryat Arba walk along what is called Worshiper's Way to reach the tomb. The gravel path skirts a Palestinian neighborhood in Hebron before climbing a steep hill.

The attack Friday night occurred just after most of the worshipers had returned to the settlement. Two soldiers in a jeep came under fire and were killed. Weinberg raced over, and he, too, was killed.

One of the Palestinian gunmen then backed down a narrow side street, luring border police and soldiers into an ambush. Two other gunmen opened fire with assault rifles and grenades, killing five police officers and wounding others.

The gunmen darted from house to house, taking cover in small olive groves and behind stone walls. Hundreds of shots were fired in all directions, peppering homes and sending many Palestinians diving for cover under their beds.

"It was very massive shooting from a short distance," said Col. Noam Tibon, the new Hebron Brigade commander. "It was dark. Like in any battle, sometimes you have a big success and sometimes a big loss."

Most of the deaths occurred during the first confusing moments as soldiers and police rushed into the alley. Troops regrouped and were able to kill two of the gunmen in a house close to the pathway. The body of another was found in a nearby field. The radical Islamic Jihad militant group claimed responsibility for the attack.

The Israeli army has repeatedly entered Hebron in force, most recently in July after a series of suicide bombings. Troops withdrew Oct. 25 as part of an agreement for Palestinian officials to reassert control.

"We tried to give the people here a better life in order to reach quiet in this city," Tibon said, standing yesterday where most of the casualties occurred. "They took advantage of what we gave them and used it against us.

"It is the poor people of Hebron who are going to suffer," said Tibon. "Now, everything is going to go back to the way it was. The curfew. The closure. Now we have to go back with our troops. We will find the people we are looking for and destroy the Islamic Jihad in Hebron."

Israeli army bulldozers demolished three of the houses from which the gunmen fired. As Tibon spoke, Palestinian families climbed over the rubble to retrieve their belongings. One woman sat on a chair and cried.

The families said the Palestinian gunmen had forced their way into their homes. Tibon glanced over at the flattened houses and sounded ambivalent. "This is part of the tragedy," he said. "The terrorists used these houses to kill our soldiers. Nobody is really innocent. This is an ugly war."

Ayoub Rajabi, 34, lives with his wife and three children close to the site of the gunbattle. He said they hid in his bedroom for three hours listening to the bullets ricochet off the front of his house. Yesterday, he stocked up on food, preparing for the army's return.

"We will suffer, but this is normal for us," said Rajabi, a construction worker. He glanced down at the destroyed homes and the children trying to pry toys and laundry baskets from the rubble. "This is also a form of terror, isn't it?"

Elsewhere in the West Bank, Israeli soldiers shot and killed two suspected members of the Islamic Jihad in the West Bank city of Jenin after what officials described as a gunfight. Also, a Palestinian woman was killed in Nablus by shrapnel from a tank shell fired by the army.