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

The woman was the first Israeli to die in a Palestinian rocket attack since November.

Even before the fatal salvo, Hamas leaders feared 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 there at the time, was the target. But Israel’s leaders said they would employ more drastic measures to stop daily barrages of rocket fire into 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.

Other airstrikes Monday killed a Hamas militant and hit suspected weapons-storage facilities, the Israeli 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.

At sundown, a Palestinian rocket hit a car and set it on fire in the Israeli town of Sderot, about a mile from Gaza. The woman died en route to the hospital.