By IBRAHIM BARZAK
and TIA GOLDENBERG
The Associated Press
GAZA CITY, Gaza Strip -- Israeli troops pushed deeper into Gaza today to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers.
Israel launched the operation late Thursday, following a 10-day campaign of more than 2,000 air strikes against Gaza that had failed to halt relentless Hamas rocket fire on Israeli cities.
Israel's first major ground offensive in Gaza in just over five years came as Egyptian cease-fire efforts stalled. Earlier this week, Israel accepted Cairo's offer to halt hostilities, but Hamas refused, demanding that Israel and Egypt first give guarantees to ease the blockade on Gaza.
Israel had been reticent about launching a ground offensive for fear of endangering its own soldiers and drawing international condemnation over mounting Palestinian civilian deaths.
But after thousands of troops had been on standby for several days, Israeli Prime Minister Benjamin Netanyahu said he had ordered the military to prepare for a "significant expansion" of the ground offensive.
"Since it is not possible to deal with the tunnels only from the air, our soldiers are doing it also from the ground," he said before a special Cabinet meeting in Tel Aviv.
"We chose to begin this operation after the other options were exhausted and with the understanding that without the operation the price we will pay can be very high."
Throughout the night, the thud of tank shells echoed across Gaza, often just a few seconds apart. Several explosions from Israeli missile strikes shook high-rise buildings in central Gaza City and sent pillars of smoke into the sky.
The wounded were rushed to Gaza's main Shifa Hospital, including several members of the same family struck by shrapnel from tank shells. Among those hurt were a toddler and a boy of elementary school age, their bodies pocked by small bloody wounds.
Gaza health officials said at least 20 Palestinians have been killed since the ground operation began, including three teenage siblings killed by shrapnel from a tank shell attack. At the morgue, one of the victim's faces was blackened by soot and he and his siblings were each wrapped in a white burial shroud.
The Israeli military said it killed 17 militants in different exchanges of fire, while 13 were captured after surrendering. It was not immediately clear if the militants were among the casualties reported by Gaza authorities.
"The ground offensive does not scare us and we pledge to drown the occupation army in Gaza mud," Hamas spokesman Sami Abu Zuhri said in a statement.
The Israeli military said one soldier was killed in the northern Gaza Strip, the first Israeli casualty among troops. The circumstances behind the death of Staff Sgt. Eitan Barak, 20, were not immediately clear, with Hamas' military wing saying it ambushed Israeli units in the northern town of Beit Lahiya and caused casualties but Israeli media saying it was likely a case of friendly fire.
Israel's chief military spokesman Brig. Gen. Moti Almoz told Army Radio the military was investigating the circumstances behind the soldier's death.
Tanks, infantry and engineering forces were operating inside the coastal strip. The military said it targeted rocket launchers, tunnels and more than 100 other targets, and that a number of soldiers were wounded throughout the night.