Most of the fatalities were among members of the security forces of Hamas, the Islamic group that controls Gaza, but a few civilians were also among the dead, including children. Scores more Palestinians were wounded.

The reaction to the punishing attacks was swift and varied. A spokesman for President Bush called on Israel to avoid inflicting civilian casualties, although he did not call for a halt to the attacks on Hamas. Egypt condemned the raid and opened its border crossing so that the wounded could be treated, and a spokesman for Javier Solana, the foreign policy chief of the European Union, condemned Israel’s action and called for an immediate halt to the strikes.

For its part, Israel said the strikes would not only continue, but that they would be intensified.The air attack came after days of warnings by Israeli officials that Israel would retaliate for intense rocket and mortar fire against Israeli towns and villages by Hamas and other militant groups in Gaza.

On Wednesday alone, more than 60 rockets and mortars were fired, some reaching further than previously. While the rockets are meant to be deadly, and several houses and a factory were hit, sowing widespread panic, no Israelis were killed or seriously injured in the recent attacks.A shaky Egyptian-brokered truce between Israel and Hamas started to break down in early November. Hamas had originally agreed to a six-month lull, and declared it officially over when the six-month period expired on December 19.

Though Israel had been threatening to end its policy of restraint that saw only limited strikes against rocket launchers and squads in recent days, the timing of the raid came as a surprise to Gazans. It came in mid-morning, when official buildings and security compounds were filled with personnel and children were at school, and not, as many had anticipated, at night.

Expecting some kind of Israeli response, the Hamas leaders in Gaza had already been in hiding for two days.

In a statement issued immediately after the raid, the Israeli military warned that “This operation will be continued, expanded and intensified as much as will be required.”

“We face a period that will be neither easy nor short, and will require determination and perseverance until the necessary change is achieved in the situation in the south,” Ehud Barak, the Israeli Defence Minister, said.

In Waco, Texas, where President Bush is vacationing, a White House spokesman, Gordon Johndroe, said: “Hamas must end its terrorist activities if it wishes to play a role in the future of the Palestinian people. The United States urges Israel to avoid civilian casualties as it targets Hamas in Gaza.”

President Hosni Mubarak of Egypt said in a statement, “Egypt condemns the Israeli military aggression on the Gaza Strip and blames Israel, as an occupying force, for the victims and the wounded.”

At Shifa Hospital in Gaza City, scores of dead bodies were laid out in front of the morgue waiting for family members to identify them. At the Gaza City police station, at least 15 traffic police who had been training in a courtyard were killed on the spot.

The Israeli PM Ehud Olmert appealed to the Gazans to reject Hamas and the rocket launchers in an interview with the Al Arabiya Arabic satellite television station on Thursday.

In Israel, the authorities seemed braced for yet more rocket fire from Hamas. The Home Front Command declared a “special situation” in all communities up to 12 miles from the Gaza border, Israel Radio said. Bomb shelters in all those communities have been opened, and residents have been asked not to congregate out of doors and to remain in protected areas, the radio said.