Israeli military officials said the airstrikes, which went on into the night, were the start of what could be days or even months of an effort to force Hamas to end its rocket barrages into southern Israel. The operation could include ground forces, a senior Israeli security official said.
Palestinian officials said that most of the dead were security officers for Hamas, including two senior commanders, and that at least 600 people had been wounded in the attacks.
After the initial airstrikes, dozens of rockets were fired into southern Israel, where an emergency was declared. Thousands of Israelis hurried into bomb shelters amid the hail of rockets, including some longer-range models that reached farther north than ever before. One man was killed in the town of Netivot, the first death from rocket fire since it intensified a week ago, and four were wounded.
A number of governments and international officials, including leaders of Russia, Egypt, the European Union and the United Nations, condemned Israel’s use of force and also called on Hamas to end the rocket fire. But in strong terms, the Bush administration blamed Hamas for the violence and demanded that it stop firing rockets.
A military operation had been forecast and demanded by Israeli officials for weeks, ever since a rocky cease-fire between Israel and Hamas fully collapsed a week ago, leading again to rocket attacks in large numbers against Israel and isolated Israeli operations here.
Still, there was a shocking quality to Saturday’s attacks, which began in broad daylight as police cadets were graduating, women were shopping at the outdoor market, and children were emerging from school.
The center of Gaza City was a scene of chaotic horror, with rubble everywhere, sirens wailing, and women shrieking as dozens of mutilated bodies were laid out on the pavement and in the lobby of Shifa Hospital so that family members could identify them. The dead included civilians, including several construction workers and at least two children in school uniforms.
By afternoon, shops were shuttered, funerals began and mourning tents were visible on nearly every major street of this densely populated city.
The leader of the Hamas government in Gaza, Ismail Haniya, said in a statement that “Palestine has never witnessed an uglier massacre.” Later, in a televised speech, he vowed to fight Israel. “We say in all confidence that even if we are hung on the gallows or they make our blood flow in the streets or they tear our bodies apart, we will bow only before God and we will not abandon Palestine,” he said.
In Damascus, Syria, Hamas’s supreme leader, Khaled Meshal, said in an interview with Al Jazeera television that he was calling for a new Palestinian intifada against Israel, including the resumption of suicide attacks within Israel for the first time since 2005. Hamas, he said, had accepted “all the peaceful options, but without results.”
Ehud Barak, the Israeli defense minister and chairman of the Labor Party, said the military operation in Gaza would expand and deepen as necessary, adding, “There is a time for calm and a time for fighting, and this is the time for fighting.”
“We wanted to attack military targets while the terrorists were inside the facilities and before Hamas was able to get its rockets out that were stored in some of the targets,” said a top Israeli security official, briefing a group of reporters by telephone on condition of anonymity.
“Right now, we have to hit Hamas hard to stop the launching,” he added. “I don’t see any other way for Hamas to change its behavior. Hamas is not just a terrorist organization. It actually rules Gaza and is well supported by Iran with some of its leadership in Syria.”
Hamas had in recent weeks let it be known that it doubted Israel would engage in a major military undertaking because of its coming elections. But in some ways the elections have made it impossible for officials like Mr. Barak not to react, because the public has grown anxious and angry over the rocket fire, which while causing no recent deaths and few injuries is deeply disturbing for those living near Gaza.
Israeli officials said that anyone linked to the Hamas security structure or government was fair game because Hamas was a terrorist group that sought Israel’s destruction. But with work here increasingly scarce because of an international embargo on Hamas, young men are tempted by the steady work of the police force without necessarily fully accepting the Hamas ideology. One of the biggest tolls on Saturday was at a police cadet graduation ceremony in which 15 people were killed.