Israeli mortar shells struck outside a U.N. school where hundreds of Palestinians had sought refuge on Tuesday, killing at least 30 people — many of them children whose parents wailed in grief at a hospital filled with dead and wounded.
The Israeli army said its soldiers came under fire from militants hiding in the school and responded. It accused Gaza's Hamas rulers of "cynically" using civilians as human shields. Area residents confirmed the account, saying militants were seen staging attacks from the area.
Despite international criticism over civilian deaths and a diplomatic push to broker a cease-fire, Israeli said it would push on with the offensive against Hamas.
Israeli ground forces edged closer to two major Gaza towns, and a total of 70 Palestinians were killed Tuesday — with just two confirmed as militants, health officials in Gaza said. A top U.N. official called for an investigation into the mounting civilian death toll.
Past Israeli ground offensives have been cut short when an errant shell or missile hit a civilian center, leading to international outcries that forced Israel to stand down.
The explosions marked the second time in hours a U.N. school came under attack.
It was the deadliest assault since Israel sent ground forces into Gaza last weekend as part of a larger offensive against the ruling Hamas militant group that has killed more than 600 Palestinians, according to local hospital officials. Nearly half of the dead are civilians, according to U.N. and Palestinian officials.
"There's nowhere safe in Gaza. Everyone here is terrorized and traumatized," John Ging, the top U.N. official in Gaza, said after the first strike on the compound of a U.N. school killed three people in a courtyard. The school has served as a shelter for Gaza City refugees fleeing the blistering 11-day offensive.
A Palestinian rocket — one of two dozen fired from Gaza on Tuesday — wounded an Israeli infant.
Dr. Bassam Abu Warda, director of Kamal Adwan Hospital, said 36 people were killed in an Israeli strike outside a second U.N. school in the northern Gaza town of Jebaliya. The United Nations confirmed 30 were killed and 55 injured by tank shells.
In a statement, the Israeli army said an initial investigation found that "mortar shells were fired from within the school at IDF soldiers. The force responded with mortars at the source of fire. The Hamas cynically uses civilians as human shields."
The army said two Hamas militants — Imad Abu Askar and Hasan Abu Askar — were among the dead.
Two neighborhood residents confirmed the Israeli account, saying a group of militants fired mortars from a street near the school, then fled into a crowd of people in the streets. Israel then opened fire.
The residents, who spoke on condition of anonymity because they feared for their safety, said the Abu Askar brothers were known low-level Hamas militants.
The attack occurred at midafternoon, when many people in the densely populated Jebaliya refugee camp were out and about. Many of the refugees apparently stepped outside the shelter to get some air, thinking an area around a school was safe.
Palestinian militants frequently fire from residential areas. However, Mohammed Nassar, a medic who treated the wounded, said he saw no gunmen among the casualties.
Footage broadcast on Hamas' Al Aqsa TV showed gruesome scenes at the hospital. At first, medics carried in at least five younger boys who were laid out on the hospital floor. It was not clear whether they were still alive.
Other medics then started unloading bodies of older men who had been stacked up in the back of an ambulance, three high, and were dragged without stretchers. One man's legs had been turned into bloody stumps that dragged on the ground as he was pulled from the ambulance.
In later scenes, the emergency room was packed, with all beds occupied and barely a patch of ground unoccupied by either a body or a doctor. In other rooms, there were bloodstains on the floor and other bodies lying there, with medics running to take pulses.
"I saw a lot of women and children wheeled in," said Fares Ghanem, another hospital official. "A lot of the wounded were missing limbs and a lot of the dead were in pieces."
Majed Hamdan, an AP photographer, said he rushed to the scene shortly after the attacks. At the hospital, he said, many children were among the dead.
"I saw women and men — parents — slapping their faces in grief, screaming, some of them collapsed to the floor. They knew their children were dead," he said. "In the morgue, most of the killed appeared to be children. In the hospital, there wasn't enough space for the wounded."
He said there were marks of five separate explosions, all in the same area near the school.
U.N. officials say they provided their location coordinates to Israel's army to ensure that their buildings in Gaza are not targeted.
Speaking shortly after the first attack, Maxwell Gaylard, the U.N. humanitarian coordinator for the Palestinian territories, demanded an investigation.
"As one of the most densely populated places in the world, it is clear that more civilians will be killed," he said. "These tragic incidents need to be investigated, and if international humanitarian law has been contravened, those responsible must held accountable."
In Britain, Prime Minister Gordon Brown called it "the darkest moment yet for the Middle East." He said he had been in touch with world leaders, including from Egypt and Turkey, to discuss ways to forge a cease-fire.
The international Red Cross said an ambulance post was hit as well on Tuesday, injuring one medical worker.
Israel launched its offensive on Dec. 27 to halt repeated Palestinian rocket attacks on its southern towns. After a weeklong air campaign, Israeli ground forces invaded Gaza over the weekend.
Ten Israelis have died since the operation began, including a soldier who was shot on Tuesday.
United Nations staff estimate around 15,000 people have fled to 23 U.N.-run schools they have turned into makeshift refuges. U.N. food aid has halted in the northern Gaza Strip because officials fear residents would risk their lives to reach distribution centers.
Tanks rumbled closer to the towns of Khan Younis and Dir el Balah in south and central Gaza but were still several kilometers (miles) outside, witnesses said, adding that the sounds of fighting could be heard from around the new Israeli positions. Israel already has encircled Gaza City, the area's biggest city.
The rising civilian death toll has drawn international condemnations and raised concerns of a looming humanitarian disaster. Many Gazans are without electricity or running water, thousands have been displaced from their homes and residents say that with distribution disrupted, food supplies are running thin.
"This is not a crisis, it's a disaster," said water utility official Munzir Shiblak. "We are not even able to respond to the cry of the people." He said about 800,000 residents in Gaza City and northern parts of the territory had no access to running water from Tuesday. Gaza's overall population is 1.4 million people.
Israel says it won't stop the assault until its southern towns are freed of the threat of Palestinian rocket fire and it receives international guarantees that Hamas, a militant group backed by Iran and Syria, will not restock its weapons stockpile.
Visiting southern Israel, Prime Minister Ehud Olmert said he hoped to stop the offensive soon, but said it would depend on Hamas' willingness to stop attacks and stop smuggling weapons into Gaza from neighboring Egypt.
"We have no interest in endlessly continuing the campaign. It will stop when the conditions that are essential for Israel's security are met," he said in the rocket-scarred town of Sderot.
The army says it has dealt a harsh blow to Hamas, killing 130 militants in the past two days and greatly reducing the rocket fire. Hamas is believed to have 20,000 fighters.
Israeli forces have seized the main Gaza highway in several places, cutting the strip into northern, southern and central sectors. Israel also has taken over high-rise buildings in Gaza City and destroyed dozens of smuggling tunnels — Hamas' main lifeline — along the Egyptian border.
A high-level European Union delegation met with President Shimon Peres on Tuesday in a futile bid to end the violence. Commissioner Benita Ferraro-Waldner acknowledged Israel's right to self-defense, but said its response was disproportionate.
"We have come to Israel in order to advance the initiative for a humanitarian cease-fire and I will tell you, Mr. President, that you have a serious problem with international advocacy, and that Israel's image is being destroyed," she said, according to a statement from Peres' office.
Israeli leaders say there is no humanitarian crisis and that they have allowed the delivery of vital supplies.
French President Nicolas Sarkozy left Israel after a day of meetings with leaders.
Sarkozy continued to Damascus, urging Syria on Tuesday to pressure Hamas to end the fighting. His Syrian counterpart, Bashar Assad, slammed the Israeli assault on the coastal strip as a "war crime" and "barbaric," an "aggression" that Israel must halt.
In Washington, the State Department said Secretary of State Condoleezza Rice was traveling to the United Nations Tuesday to try to broker a sustainable cease-fire.
She planned meetings with Arab and European diplomats to lobby for a three-tiered U.S. truce proposal and will then attend a U.N. Security Council meeting on Gaza, spokesman Sean McCormack said.
Key elements demanded by the U.S.: an end to rocket attacks on Israel from Gaza and securing border crossings between Gaza and Israel and between Gaza and Egypt.
Israel's operation has angered many across the Arab world and has drawn criticism from countries such as Turkey, Egypt and Jordan, which have ties with Israel and have been intimately involved in Mideast peacemaking.