Gaza City and Jerusalem - As Israeli forces closed in on Gaza City, Mohammed Barbari joined the scramble by its most intrepid residents Sunday for dwindling supplies of food they would need while hunkering down at home.

    The first explosion tore through the central Firas Market at 11:30 a.m. as he approached from adjacent Palestine Square. Unable to turn his yellow Volkswagen Golf around in traffic, he kept driving toward the hail of shrapnel and the screams of scattering shoppers.

    Trapped on Omar Mokhtar Street, which bisects the sprawling complex, Barbari felt a second blast shake his car and shatter its back right window.

    He saw a man lying in the street with both legs severed.

    "God protect us!" the 31-year-old father of five recalled thinking.

    Medical workers said two Israeli tank shells struck the market a minute apart, killing five Palestinian civilians.

    An additional 40 wounded people were bundled into private cars for a harrowing drive to the city's Shifa Hospital, which has been overwhelmed by victims of Israel's offensive on the Hamas-ruled Gaza Strip.

    Israeli leaders say the ground assault they began late Saturday, after eight days of airstrikes, is meant as a lesson to Hamas: The Jewish state does not shrink from confronting its enemies; it fully intends to halt the militant group's near-daily rocket fire at southern Israeli communities.

    But to Gaza's 1.5 million residents, the advance of thousands of troops backed by tanks and helicopter gunships carries a different message: No place in the densely populated 140-square-mile enclave, about one-third the size of Los Angeles city, is safe.

    The ground fighting has imposed not only mortal danger, but also a new level of hardship on a people who already were suffering from shortages of electricity, water, cooking gas and other basic supplies amid an Israeli blockade.

    "Anyone who survives this wave, it will be like they were born again," said Mahmoud Musa, 55, a first-grade teacher in Deir al Balah.

    As the front line moved ever closer, ambulance sirens wailed and the sky filled with smoke. With nowhere to flee, most of the city's 400,000 residents huddled indoors.

    Firas Market, normally jammed at midday, held only about 100 shoppers at the time of the shelling, a factor in the relatively low casualty toll.

    Afterward, the market's few functioning shops promptly closed. The city's streets emptied, save for long lines of people outside the few bakeries with enough flour and generator fuel to make bread.

    Medical workers said 18 civilians were killed in Gaza on Sunday by Israeli shelling and airstrikes. Israel insisted that it was hitting Hamas targets and was not aware of any shelling in Gaza City.

    The civilian toll is likely to rise, along with international protests, as the offensive puts Israeli soldiers, Hamas fighters and civilians in ever closer proximity. Military analysts say Israel's leaders and commanders fully considered that risk before launching the assault.

    "The guiding principle behind the ... operation is ... we are moving in with full force, shooting everything we have, including artillery," Alex Fishman, an Israeli military affairs correspondent, wrote Sunday in the newspaper Yediot Aharonot. "We'll pay the international price later for the collateral damage and the anticipated civilian casualties."

    Many in Gaza said they felt helpless because Israel had so far resisted calls for a cease-fire and an easing of its crippling blockade on the territory.

    "The world knows we are running out of everything, and no one moves a finger," said Ahmed Dalloul, who was cooking over a trash fire on the balcony of his Gaza City apartment. "Let them feel what we feel. Let the whole silent, unfair world suffer as we suffer."

    Sewage is spilling into Gaza's streets and more than half a million residents have no water supply after bombardments destroyed electricity lines, shutting down pumping stations, officials said. The phone company said 90% of Gaza's cellular service is down.

    Doctors at Shifa Hospital said its generators barely have enough fuel to last through the week and run the machines that keep 30 infants and 40 other patients alive in the ICU.

    Like the doctors, nearly everyone in Gaza is scrounging for scarce fuel.

    Determined to find a distraction, teenagers Abdul Aziz Bulan and Karim Ali begged cash from their neighbors in Deir al Balah. They bought enough generator fuel to power the television set in Ali's parents house for Sunday's Spanish league soccer match between Barcelona and Majorca.

    Abu Alouf is a special correspondent. Special correspondent Ahmed Burai in Deir al Balah contributed to this report.