JERUSALEM AND GAZA CITY — Israeli soldiers and tank columns bisected the Gaza Strip on Sunday, isolating its largest city amid fierce clashes on multiple fronts with militant fighters.
At least 35 Palestinians died in confrontations with Israeli troops and from missile strikes and artillery barrages, according to local medical sources. More than 500 Palestinians have been killed since Dec. 27, when Israel began its current campaign against Hamas, the militant group that controls the Gaza Strip. At least 2,000 Palestinians have been wounded.
In the face of mounting international calls for a cease-fire, including sharp criticism from the head of the United Nations, Israeli leaders pledged to continue their campaign to stop rocket launches by Gazan militants at southern Israeli cities and towns.
"This operation was unavoidable," Israeli Prime Minister Ehud Olmert told his Cabinet on Sunday.
Olmert said the campaign, which started with a week of punishing airstrikes and escalated to a land incursion Saturday evening, was needed to "change the security reality in the south."
Despite the massive advantage of the Israeli military, which cut off heavily populated Gaza City, militant groups in the enclave managed to continue firing rockets and mortar shells into southern Israel. At least 40 rockets were launched Sunday, hitting cities and towns that included Ashkelon, Ashdod, Netivot and Ofakim. They caused widespread panic but only minor injuries, according to the Israeli army.
Although the homemade rockets are wildly inaccurate, Hamas has increased their range in recent weeks, and three Israeli civilians have been killed by projectiles launched from Gaza since the start of hostilities. Israeli officials say about 900,000 of their citizens are within range of the rocket fire and live in fear of sudden attack.
Throughout the Gaza Strip, the enclave's 1.5 million Palestinian residents for the most part huddled indoors for safety, most venturing out only to line up for dwindling supplies of bread and household goods.
Dr. Moawiya Hassanein of Gaza City's main Shifa Hospital said more than half the day's casualties were civilians, including a mother and her four children killed by an Israeli tank shell east of Gaza City. The militant casualty count was probably much higher, Hassanein said, but it was too risky for ambulances and rescue crews to approach the conflict zone.
One ambulance, funded by the international aid organization Oxfam, was struck by an Israeli shell while trying to evacuate injured from the front-line community of Beit Lahiya, the organization announced. The impact killed one paramedic; a second paramedic lost his foot.
"The incident shows yet again that trying to fight a military campaign in the densely populated streets and alleys of the Gaza Strip will inevitably lead to civilian casualties. There are no safe areas, and Gazans who want to flee the fighting have been prevented from leaving the strip," said Oxfam Country Director John Prideaux-Brune in Jerusalem.
It is difficult to get independent reports of the fighting because most foreign media have been barred from the territory.
At least two Israeli armored thrusts sliced deep into the narrow coastal territory, cutting off Gaza City's approximately 400,000 residents from the rest of the strip. One force fought into the edges of the Jabaliya refugee camp, north of Gaza City; a second force pushed into the abandoned Jewish settlement of Netzarim, several miles south of Gaza City. Israel left Netzarim, along with other settlements, when it pulled out of Gaza in 2005.
The Netzarim incursion essentially cuts the tiny, densely packed territory into two parts. Hassanein, the Shifa Hospital official, said there were 20 truckloads of desperately needed medical aid in the southern end of the enclave unable to reach Gaza City, where most of the casualties were being brought.
As of late Sunday, Israeli forces had yet to enter any of Gaza's major population centers. Any attempt to do so would probably prompt a fierce and bloody street-to-street battle against militant forces with intimate knowledge of the dense urban terrain.
Reliable details from the battlefield were difficult to obtain Sunday night, with both Israel and Hamas making unconfirmed claims of casualties inflicted on the other side. Hamas' military wing released a statement saying its fighters had killed nine Israeli soldiers and destroyed three tanks.
The Israeli army announced that one of its soldiers had been killed and another seriously injured in an exchange of gunfire near Jabaliya, and that 18 soldiers had been moderately injured. An army spokesman said that "dozens of Hamas gunmen had been hit," but wouldn't speculate on how many were killed or wounded.
U.N. Secretary-General Ban Ki-moon conveyed his "extreme concern and disappointment" over the death toll in a phone call to Olmert and sought an immediate end to the operation.