Gaza City, Gaza Strip - Israeli warplanes retaliating for rocket fire from the Gaza Strip pounded dozens of security compounds across the Hamas-ruled territory in unprecedented waves of airstrikes Saturday, killing nearly 200 people and wounding 270 others in the single bloodiest day of fighting in years.

    Most of those killed were security men, but civilians were also among the dead. Hamas said all of its security installations were hit and responded with several medium-range Grad rockets at Israel, reaching deeper than in the past. One Israeli was killed and at least four people were wounded in the rocket attacks. With so many wounded, the Palestinian death toll was likely to rise.

    The air offensive followed weeks of intense Palestinian rocket and mortar fire on southern Israel, and Israeli leaders had issued increasingly tough warnings in recent days that they would not tolerate continued attacks.

    Defense Minister Ehud Barak said Israel would expand the operation if necessary. "There is a time for calm and there is a time for fighting, and now is the time for fighting," he told a news conference. He would not comment when asked if a ground offensive was planned.

    But asked earlier if Hamas political leaders might be targeted next, military spokeswoman Maj. Avital Leibovich said, "Any Hamas target is a target."

    The strikes caused widespread panic and confusion in Gaza, as black clouds of smoke rose above the territory, ruled by Hamas for the past 18 months. Some of the Israeli missiles struck in densely populated areas as children were leaving school, and women rushed into the streets frantically looking for their children. Most of those killed were security men, but civilians were among the dead.

    Said Masri sat in the middle of a Gaza City street, close to a security compound, alternately slapping his face and covering his head with dust from the bombed-out building.

    "My son is gone, my son is gone," wailed Masri, 57. The shopkeeper said he sent his 9-year-old son out to purchase cigarettes minutes before the airstrikes began and now could not find him. "May I burn like the cigarettes, may Israel burn," Masri moaned.

    In Gaza City's main security compound, bodies of more than a dozen uniformed security officers lay on the ground. One survivor raised his index finger in a show of Muslim faith, uttering a prayer. The Gaza police chief was among those killed. One man, his face bloodied, sat dazed on the ground as a fire raged nearby.

    Later, some of the dead, rolled in blankets, were laid out on the floor of Gaza's main hospital for identification. Hamas police spokesman Ehad Ghussein said about 140 Hamas security forces were killed.

    Israeli military officials said more than 100 tons of bombs were dropped on Gaza by mid-afternoon. They spoke on condition of anonymity under military guidelines.

    Defiant Hamas leaders threatened revenge, including suicide attacks. Hamas "will continue the resistance until the last drop of blood," vowed spokesman Fawzi Barhoum.

    Israel told its civilians near Gaza to take cover as militants began retaliating with rockets, and in the West Bank, moderate Palestinian President Mahmoud Abbas called for restraint. Egypt summoned the Israeli ambassador to express condemnation and opened its border with Gaza to allow ambulances to drive out some of the wounded.

    Israeli leaders approved military action against Gaza earlier in the week.

    Past limited ground incursions and air strikes have not halted rocket barrages from Gaza. But with 200 mortars and rockets raining down on Israel since the truce expired a week ago, and 3,000 since the beginning of the year, according to the military's count, pressure had been mounting in Israel for the military to crush the gunmen.

    Gaza militants fired 30 rockets and mortars Saturday after the air offensive began. A missile hit the town of Netivot, killing an Israeli man and wounding four people, rescue services said.

    Dozens of stunned residents gathered around the house that took the deadly rocket hit. Many wept openly. The crowd broke up after an alert siren went off and sent the onlookers running.

    Streets were nearly empty in Sderot, the Israeli border town that has been pummeled hardest by rockets. A few cars carried panicked residents leaving town. Dozens of people congregated on a hilltop to watch the Israeli aerial attacks.

    Israel declared a state of emergency in Israeli communities within a 12-mile (20-kilometer) range of Gaza, putting the area on a war footing. A siren went off in Kiryat Gat, about 12 miles (20 kilometers) from the border, but early reports that the town was hit by a rocket for the first time were incorrect.

    Barak, the Israeli defense minister, said the coming period "won't be easy" for southern Israel.

    Protests against the campaign erupted in the Abbas-ruled West Bank and across the Arab world.

    Several hundred angry Jordanians protested outside a U.N. complex in the capital Amman. "Hamas, go ahead. You are the cannon, we are the bullets," they cried, some waving the signature green Hamas banners.

    In Ein Hilweh, a Palestinian refugee camp in Lebanon, dozens of youths hit the streets and set fire to tires. In Syria's al-Yarmouk camp, outside Damascus, dozens of Palestinian protesters vowed to continue fighting Israel.

    The first round of air strikes on Gaza came just before noon.

    Hospitals crowded with people, civilians rushing in wounded people in cars, vans and ambulances. "We are treating people on the floor, in the corridors. We have no more space. We don't know who is here or who to treat first," said one doctor who hung up the phone before identifying himself at Shifa Hospital, Gaza's main treatment center.

    Dr. Moawiya Hassanain, a Gaza Health Ministry official, said at least 192 people were killed and 270 wounded. Frantic civilians drove wounded people to hospitals in their cars.

    In the West Bank, Hamas' rival, Abbas, said in a statement that he "condemns this aggression" and called for restraint, according to an aide, Nabil Abu Rdeneh. Abbas, who has ruled only the West Bank since the Islamic Hamas seized power in Gaza in June 2007, was in contact with Arab leaders, and his West Bank Cabinet convened an emergency session.

    Israel has targeted Gaza in the past, but the number of simultaneous attacks was unprecedented.

    Israel left Gaza in 2005 after a 38-year occupation, but the withdrawal did not lead to better relations with Palestinians in the territory as Israeli officials had hoped.

    Instead, the evacuation was followed by a sharp rise in militant attacks on Israeli border communities that on several occasions provoked harsh Israeli military reprisals.

    The last, in late February and early March, spurred both sides to agree to a truce that was to have lasted six months but began unraveling in early November.