Updated

Israeli-Palestinian violence escalated dangerously Monday when Israel killed five militants in airstrikes and indicated that Hamas political leaders could be their next target, and a rocket fired from Gaza killed an Israeli woman, inviting a harsh Israeli response.

The rocket fired at the battered town of Sderot hit a car, setting it on fire. Officials said the woman died on the way to the hospital.

She was the first Israeli killed in a rocket attack since November. The salvo came during a meeting in Sderot between Israeli Foreign Minister Tzipi Livni and Javier Solana, the European Union foreign policy chief. They were not harmed.

David Baker, an Israeli official who was in Sderot for the meeting, said Israel would "not tolerate this type of terror," and "Israel is fully determined and fully prepared to take to the necessary actions to bring the Qassam attacks to an end."

Even before the fatal salvo, Hamas leaders were fearing for their safety. They turned off their cell phones, stayed out of official vehicles and reduced their movements as militant groups declared a state of emergency.

The precautions followed an Israeli airstrike late Sunday on the home of Hamas lawmaker Khalil al-Haya that killed eight people. Israel denied al-Haya, who was not home at the time, was the target. But Israel's leaders said they would employ more drastic measures to stop the daily salvos of rocket fire from Gaza at Israel.

On Monday, an Israeli aircraft fired a missile at a car carrying four Islamic Jihad men, killing all of them. A spokesman for the group said they were targeted just after firing rockets into Israel. The military confirmed the attack. Islamic Jihad, which has carried out hundreds of rocket attacks and suicide bombings in recent years, threatened "earthshaking" revenge.

Other airstrikes Monday killed a Hamas militant and hit suspected weapons-storage facilities, the army said. More than 40 Palestinians have been killed in Israeli strikes since a decision last week to start hitting back for the rocket barrages.

Hamas pledged to "strike at the enemy anywhere in Palestine, whether with suicide attacks or operations against soldiers," said Hamas military wing spokesman Abu Obeida. Since 2000, Hamas has carried out dozens of suicide bombing attacks in Israel, killing more than 250 people.

The Israeli strikes have not slowed the rocket barrages. At least 18 rockets were fired at Israel Monday, the military and Israeli media said, bringing the total over the past week to more than 150. The homemade rockets have disrupted life in Israeli towns near Gaza. A direct hit on Sunday destroyed a popular Indian restaurant.

A Security Cabinet decision on Sunday to step up measures against militants, prompted calls to target the Hamas political leadership. "I say we have to put them all in the crosshairs," Cabinet minister Binyamin Ben-Eliezer, a retired army general, told Israel Radio.

Government spokeswoman Miri Eisin pointedly did not rule out the possibility. "What was decided yesterday in the security meeting is that all terrorists, including those that plan attacks, call for attacks or carry out attacks, are not immune," she said. "We cannot differentiate between those who call for attacks and those who carry out attacks."

In 2004, at the height of Palestinian-Israeli violence, Israel killed the founder of Hamas, wheelchair-bound Sheik Ahmed Yassin, and his successor, Abdel Aziz Rantisi, in airstrikes just weeks apart. Israeli officials have said that the assassinations frightened the Hamas leadership and caused a significant reduction in its attacks, especially suicide bombings.

Now, however, Hamas is the dominant element in the Palestinian government, sweeping to power in a 2006 election. Prime Minister Ismail Haniyeh is the most visible Hamas political leader.

He and other Hamas leaders attended a mass funeral Monday for the Palestinians killed in the airstrike next to al-Haya's house. Addressing the crowd of tens of thousands, Haniyeh said they were being targeted "because you are supporters of resistance in Palestine." He called on his people to persist "until we achieve either victory or martyrdom."

After the public event, Hamas leaders went at least partially underground, turning off their cell phones to avoid detection by Israel, avoiding official vehicles and restricting their movements.

"We have to be careful," Hamas official Ayman Taha said. "The target was Khalil al-Haya yesterday." U.S. Ambassador Richard Jones gave a boost to the Israeli campaign, but urged Israel to do its best to avoid harming civilians.

"We constantly urge Israel to target its response as closely as possible at those who are responsible for the actions, and to avoid innocent collateral damage," Jones said at an academic conference.