Israel said it has inflicted a heavy blow against Hamas as it expands a weeklong offensive meant to stop rocket fire on southern Israel. But spiraling civilian casualties among Palestinians fueled an international outcry, even as the U.S. blocked approval of a U.N. Security Council statement Saturday night calling for an immediate cease-fire.
Israel's ground forces moved in after nightfall Saturday following hours of intense, fiery artillery shelling to clear the way, and Hamas warned that its fighters would turn Gaza into an Israeli "graveyard."
On Sunday, Israeli soldiers fought primarily in open areas in the launching zones used by Gaza's militants to send rockets raining down on Israeli cities. As the troops in three brigade-size formations moved in, residents of those Israeli cities began cautiously emerging from bomb shelters in hopes that the rocket fire would taper off.
Backing up the troops, mobile artillery units fired shells that exploded in veils of white smoke over Gaza's urban skyline. Tanks pushed south of Gaza City as deep as the abandoned settlement of Netzarim, which Israel left along with other communities when it pulled out of Gaza in 2005.
That effectively cut off Gaza City, the territory's largest population center with about 400,000 residents, from the rest of Gaza to the south.
Israel's military chief said Hamas fighters were trying to draw soldiers deeper into Gaza's sprawling, densely packed urban
areas, where the military said militants were shielding themselves behind civilians.
"You entered like rats," Hamas spokesman Ismail Radwan told Israeli soldiers in a statement on Hamas' Al Aqsa TV. "Gaza will be a graveyard for you, God willing."
Israeli forces have not yet entered urban areas, said Brig. Gen. Avi Benayahu, the chief army spokesman. He warned, however, that the operation was not a "school trip" and would be long and demanding.
The ground invasion risks turning into intense urban combat, with house-to-house fighting, sniper fire and booby-traps. Hamas is believed to have about 20,000 gunmen and has had time to prepare.
To guard against hidden explosives, Israel's ground forces moved through fields and orchards with bomb-sniffing dogs.
Since the ground assault began, 64 Palestinian civilians have been killed, said Dr. Moaiya Hassanain, a Health Ministry official. The new deaths brought the death toll in the Gaza Strip to more than 512 since Dec. 27. The tally is based on figures from the U.N. and Palestinian health officials as well as a count by The Associated Press.
Five Israelis have been killed since the offensive began. One soldier was killed in the ground operation and about 40 were wounded, some of them in heavy exchanges of fire near the militant stronghold of Jebaliya, a town on Gaza City's northern outskirts, the army said. Heavy Israeli casualties could undermine what has so far been overwhelming public support for the operation.
At one hospital in the northern village of Beit Lahiya, medics carrying three injured children in their arms rushed them to treatment. One of the children had a blood-soaked bandage wrapped around his head and covering his eyes.
An Israeli shell also struck an ambulance in the town, killing a paramedic, said Marwan Abu Ras, a hospital administrator. The relief organization Oxfam, which said the ambulance belonged to a partner organization, al-Awda Hospital, confirmed the shelling.
An airstrike hit another ambulance belonging to the Hamas-run Health Ministry in Gaza City, killing three other paramedics, said medic Jamal Hawajiri. That ambulance crew was driving to a Hamas training site where there were reports of wounded.
An Israeli army spokesman said he had no information on the incidents.
The Israeli army said it had killed dozens of armed Hamas gunmen, but Gaza officials could confirm only a handful of dead fighters.
Condemnation of Israel's ground operation poured in from the Middle East and Europe.
"The violence has to stop," said EU External Relations Commissioner Benita Ferrero-Waldner.
U.S. officials maintained their firm support for Israel and squarely blamed Hamas.
Vice President Dick Cheney said Israel "didn't seek clearance or approval from us" before pushing into Gaza.
Sens. Harry Reid and Dick Durbin - the top two Democrats in the chamber - and Senate Republican leader Mitch McConnell all described Israel's actions as understandable.
"I think what the Israelis are doing is very important," Reid said. "I think this terrorist organization, Hamas, has got to be put away. They've got to come to their senses."