GAZA CITY, Gaza Strip (AP) -- Israel seized control of high-rise buildings and attacked houses, mosques and smuggling tunnels as it pressed its offensive against the Gaza Strip's Hamas rulers on Monday, even as a stream of European leaders headed to the region to push for a truce.
At least 10 Palestinian children were killed, raising the known death toll from a new ground invasion to more than 80, a Palestinian health official said. The vast majority of confirmed deaths have been civilians, fueling international outrage. Gaza's biggest hospital said it was overwhelmed, its morgue jammed and its hallways filled with the wounded.
As the bruising campaign against Gaza's Hamas rulers entered its 10th day, the Islamic militant group continued to pummel southern Israel with more than two dozen rockets on Monday and promised to wait for Israeli soldiers "in every street and every alleyway."
Israeli Defense Minister Ehud Barak said the offensive would go on until Israel achieved "peace and tranquility" for residents of southern Israel.
After a weeklong air offensive, Israeli ground troops invaded Gaza late Saturday. The Israelis have seized a main highway in Gaza, slicing the territory in half. Israeli forces also pounded houses, a pair of mosques and smuggling tunnels on Monday as they pressed forward with the offensive.
Israel has attacked several mosques during the campaign, saying they were used to store weapons. One house also attacked belonged to a leading Hamas lawmaker, who was not inside at the time.
The Israeli army said "dozens" of militants have been killed or wounded.
Gaza health officials reported 537 Palestinian dead and nearly 2,000 wounded since Israel embarked upon the campaign on Dec. 27. At least 200 civilians were among the dead.
Israel has three main demands: an end to Palestinian attacks, international supervision of any truce and a halt to Hamas rearming.
Hamas demands a cessation of Israeli attacks and the opening of vital Gaza-Israel cargo crossings, Gaza's main lifeline.
Israeli forces seized sparsely populated areas in northern Gaza and by Monday morning were dug in on the edges of Gaza City.
Further movement into the heart of the built-up areas would mean deadly urban warfare, with house-to-house fighting, sniper fire and booby traps in crowded streets and alleyways familiar to Hamas' 20,000 fighters.
Israeli forces have been training in a mock Arab city for more than two years to prepare for urban warfare in Gaza, said Leibovich, the military spokeswoman.
"They are prepared, if necessary," to enter Gaza's cities, Leibovich said. She wouldn't disclose whether troops would definitely enter Gaza's cities.
Gaza's biggest hospital, Shifa, was swamped by the bloodshed. Bodies were two to a morgue drawer, the wounded were being treated in hallways because beds were full, and three preschool boys killed in an artillery strike Monday were laid out on a floor.
Since Israel mounted its ground offensive three days ago, most of the dead and wounded arriving at Shifa have been civilians, including 16 who died in various attacks across Gaza on Monday.
Ten of them were children, said health official Dr. Moaiya Hassanain.
Four young siblings were killed in a missile strike on a house east of Gaza City, Hassanain said. Three other children died in a naval shelling of a Gaza City beach camp, and three toddlers died in an attack on another town outside Gaza City, another Gaza health official said.
In addition, three adults died when a missile struck near a house of mourning in the northern town of Beit Lahiya, and three other adults died in attacks elsewhere, Hassanain said.
Israeli troops seized three six-story buildings on the outskirts of Gaza City, taking up rooftop positions after locking residents in rooms and taking away their cell phones, a neighbor said, quoting a relative in one of the buildings before his phone was taken away.
"The army is there, firing in all directions," said Mohammed Salmai, a 29-year-old truck driver. "All we can do is take clothes to each other to keep ourselves warm and pray to God that if we die, someone will find our bodies under the rubble."
Civilian casualties have spiked since Israel launched the ground offensive. Of the 80 confirmed deaths, at least 70 were civilians, Hassanain said.
Leibovich, the military spokeswoman, said Hamas was to blame for civilian casualties because it operates in densely populated areas.
"If Hamas chose cynically to use those civilians as human shields, then Hamas should be accountable," she said. "Civilians will probably continue to get killed, unfortunately, because Hamas put them in the first lines of fire."
Black smoke from tank shells and wind-swept dust billowed in the air over Gaza City, while white smoke from mortar shells rose in plumes above a main road leading to northern Gaza that the Israeli military seized on Sunday, cutting off Gaza's north from its south. Explosions could be heard in Gaza City as aircraft attacked buildings.
The streets of Gaza City, home to 400,000 people, were almost empty. Two children crossing a street near a Hamas security compound didn't bother to look right and left for cars but gazed up at the sky, apparently looking for attack aircraft. The only vehicles on the road were fire engines, ambulances and press cars.
Unmanned Israeli planes and Apache helicopters circled overhead.
Hamas leaders went into hiding before the Israeli military strike began and only on rare occasions have addressed the Gaza residents in broadcasts from their hideouts.
On Monday, the mastermind of Hamas' 2007 takeover of Gaza, Mahmoud Zahar, exhorted Palestinians to "crush" Israeli forces and to target Israeli civilians.
"The Zionists have legitimized the killing of their children by killing our children. They have legitimized the killing of their people all over the world by killing our people," Zahar said in a grainy video broadcast on Hamas TV. "Crush your enemy," he urged.
A spokesman for Hamas' military wing, identified by a nom de guerre, Abu Obeida, said the Islamic militants will fire more rockets deeper into Israel. His face concealed behind a trademark red mask, he appeared on Hamas' Al Aqsa TV on Monday, standing before a map of Israel with crosses marking previous areas hit by Hamas rockets and circles for areas Hamas intends to hit.
He warned Israeli ground forces that "we prepared for you thousands of mighty fighters, who wait for you in every street and every alleyway."
Hamas security said Israeli aircraft struck two mosques in central and northern Gaza, while ground troops battled with militants armed with mortar shells, grenades and anti-tank missiles in the area between Gaza City, Gaza's largest urban area, and Jebaliya to the north.
The ground clashes took place in open areas militants use to launch rockets and mortars at nearby Israeli communities, but did not advance into urban areas where casualties are liable to swell.
The Israeli military said aircraft carried out 30 sorties overnight, striking a mosque in Jebaliya that contained a large store of weapons, and an underground arms bunker in the Gaza City area that touched off secondary explosions and collapsed underground smuggling tunnels.
Aircraft also hit weapons smuggling tunnels in southern Gaza near the Egyptian border and went after the houses of Hamas members where weapons were stored, the military said. A rocket launcher and suspected anti-aircraft missile launcher were also targeted, it said.
The violence has deepened the suffering in impoverished Gaza, home to 1.4 million people. The military said Monday that 80 truckloads of humanitarian aid and critical fuel supplies would be let in.
Israel's ground operation is the second phase in an offensive that began as a weeklong aerial onslaught aimed at halting Hamas rocket fire that now threatens major cities and one-eighth of Israel's population of 7 million people.
Five Israelis have been killed since the offensive began, including a soldier who died in the ground operation. Heavy Israeli casualties could undermine what has so far been overwhelming public support for the operation.
French President Nicolas Sarkozy, who unsuccessfully proposed a two-day truce before the land invasion began, was due to meet with Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas, who lost control of Gaza to Hamas in June 2007.
While blaming Hamas for causing Palestinian suffering with rocket fire that led to the Israeli offensive, Sarkozy has condemned Israel's use of ground troops, reflecting general world opinion. Sarkozy and other diplomats making their way to the region are expected to press hard for a cease-fire.
The Czech Republic, which took over the 27-nation EU's presidency on Thursday, urged Israel to allow humanitarian relief aid into Gaza. German Chancellor Angela Merkel spoke on the phone Sunday with Olmert and advocated a quick cease-fire in Gaza, her government said. Merkel also called for an end to the smuggling of weapons into the Gaza Strip.
Teibel reported from Jerusalem.
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