Gaza Death Toll Mounts Amid Cease-Fire Talks

Israeli missiles crashed into two U.N. schools today, killing at least 30 people in one school and three more in the other attack as the chaotic fighting in Gaza became deadlier than ever.

The attacks on the schools are certain to heighten international outrage over Israel's Gaza offensive as well as diplomatic pressure for a cease-fire.

French President Nicolas Sarkozy and Egyptian President Hosmi Mubarak proposed a plan to halt the fighting today, which Palestinian President Mahmoud Abbas endorsed. With the plan's details not yet released, French Foreign Minister Bernard Kouchner said the proposed cease-fire plan would bring together the main parties to end the violence and discuss critical issues like reopening all crossings.

VIDEO: Dozens of Palestinian Civilians KilledPlay

"I am sure that it will be considered and you will find out whether it was accepted," Israeli Ambassador Gabriela Shalev told reporters, according to Reuters. "But we take it very, very seriously."

Sarkozy went to Syria and asked the Syrian government to use its influence on Hamas to stop it from firing rockets at Israeli towns.

Secretary of State Condoleezza Rice and Palestinian President Mahmoud Abbas were scheduled to meet at the United Nations in New York today, but there was little indication that a cease-fire deal was in reach.

Meanwhile the carnage has increased as fighting has edged closer to Gaza's teeming population centers. Hamas fighters are battling back with suicide attackers, Israeli "friendly fire" was blamed for the death of four troopers and whole families are being killed while huddling in their homes.

VIDEO: Israelis strike schools in Gaza.Play

As many as 640 Palestinians have died, and 2,850 have been wounded in the 11 days of fighting so far, according to Palestinian medical sources. Close quarter fighting between Israeli troops and Hamas fighters on the outskirts of Gaza City is proving costly for both sides.

Six Israeli soldiers have been killed and 70 wounded, according to the Israeli military.

The heaviest toll came today when an Israeli missile slammed into a U.N. school in Jabaliya.

John Ging, director of U.N. refugee operations in Gaza, said there were at least 30 dead at the school and 55 injured, including five who were critically wounded. Palestinian sources in Gaza, however, told ABC News that more than 40 died in the school rubble.

VIDEO: Israeli missiles hit two schools in Gaza, killing at least 30 people.Play

"The situation is horrific at the moment," Ging said. "There is no safe sanctuary for Palestinians."

Ging said 350 people had sought refuge in the girls' school. The U.N. said the school was clearly marked and its Global Positioning System location was registered with the Israelis.

A spokesman for the Israeli Defense Forces said an initial inquiry determined that Israeli forces fired a volley of mortar rounds at the school in retaliation for several mortar rounds that were allegedly fired at them from the school grounds.

"There were quite few Hamas militants inside the school. They were launching rockets at our force," said Israeli army spokesman, Maj. Avital Leibovitch.

Israel said the bodies of two Hamas operatives were found among the dead at the school.

"This is not the first time that Hamas has fired mortars and rockets from schools, in such a way deliberately using civilians as human shields in their acts of terror against Israel," the IDF statement said.

U.N. officials said three mortar rounds landed within the school's perimeter.

A second U.N. school in Gaza City that housed 400 refugees from the violence was struck during the night. Three people were reportedly killed in that attack.

Ging said 14,000 people had sought refuge in 23 U.N. schools throughout the Gaza Strip because their homes were destroyed or to escape violence.

After the first school was hit, Maxwell Gaylard, the U.N. humanitarian coordinator for the occupied Palestinian territory, issued a statement saying, "These tragic incidents need to be investigated, and if international humanitarian law has been contravened, those responsible must held accountable."

Hamas Suicide Attackers

In areas outside of Gaza City in the north and Khan Younis in Gaza's south, the sound of missiles, rockets, artillery, tank shells and gunfire could be heard and seen on local television throughout the night.

One Israeli officer who did not want to be named compared the fight to dentistry, saying, "We're not going in for a filling. We want to do a root canal."

By morning Israeli tanks rolled into the outskirts of Khan Younis where they were met by some of the toughest resistance yet.

According to an Israeli source, Hamas has employed a tactic of using small squads of fighters with one or more suicide bombers taking the lead. The suicide bomber launches an initial attack at Israeli soldiers to "shock the ground troops" while the remaining Hamas fighters try to take Israeli soldiers hostage. So far this tactic has proved unsuccessful.

Hamas also fired off 36 more rockets today, with one landing in the Israeli town of Gadera, just 17 miles south of Tel Aviv.

The heaviest blow delivered against Israeli forces came in two incidences of friendly fire.

In Sajaiyeh neighborhood of Gaza City, a tank shell struck a home killing one Israeli Golani (or infantry) officer and two Golani soldiers and injuring 24 others. A source with knowledge of the incident said that the soldiers were trying to find shelter in the empty house from mortar shells. The tank crew thought the armed men inside the house were Hamas fighters and fired. The house then collapsed on the soldiers.

In the second incident an Israeli officer was killed around 10 p.m., close to Beit Hanoun in northern Gaza, by what sources say was a tank shell. A source in the southern command said that a force of infantry paratroopers was engaged in heavy fire exchanges with Hamas and requested artillery assistance. There were a few tanks firing in that area at the same time and the source said that one of the shells probably killed the officer. Two soldiers were also injured in the process. Both incidents are under investigation.

The Israeli military says while the friendly fire incidents are regrettable their ground offensive is producing results. At least 130 Hamas fighters have been killed since the ground operation began and an additional 100 have been taken captive, military sources tell ABC News.

Israel Claims to Kill Hamas Military Leaders

The Israeli military also confirmed that it had killed Iman Siam, the head of Hamas' rocket launching program. The Israeli military says Siam "founded the organization's rocket launching program" and was "the head of Hamas' artillery program throughout the Gaza Strip."

Stopping the rocket attacks was why Israel invaded Gaza, but the rockets continued to zoom out of Gaza toward towns in southern Israel. An additional 26 rockets were fired so far today.

Israel also claimed to have killed four Hamas fighters ranging from a battalion commander to a senior commander.

Israeli military sources say that of the approximately 15,000 trained Hamas fighters in Gaza, there are about 1,000 who have received additional training and operate in leadership roles. Israel's military says taking out even a few Hamas leaders could strike a devastating blow to the organization.

The intensified fighting is increasing the number of civilian casualties. Medical sources in Gaza report that 35 Palestinians were killed through the night and that 28 of them were civilians.

In total, more than 600 Palestinians have been killed in the 11-day Israeli campaign and nearly 3,000 injured. The United Nations says 25 percent of the casualties are women and children.

In Gaza, the victims are finding there is no place to hide. Seventy-one Palestinians were killed in today's violence alone, Gaza health officials say.

In the Toufah neighborhood east of Gaza City, a tank shell tore into a home killing all 13 members of an extended family, according to ABC News producer Sami Zyara.

In a heart-wrenching scene at a Gaza hospital Monday night, a man held the lifeless body of his 3-month-old son. The boy was carefully wrapped in blankets, a bandage around his head. There was little doctors could do. The child died from wounds suffered in the fighting. Tears rolling down his face, the father kissed his son goodbye.

The Israeli military says it does not target civilians and officials stress that Hamas hides behind civilians and launches its rockets and mortars from civilian areas making it difficult for Israeli missiles to avoid collateral damage.

Dr. Mads Gilbert, a Westerner who has been working in Gaza's Al Shifa hospital during the Israeli offensive, said there was no doubt in his mind that Israel is targeting civilians.

"Among the injured," Gilbert told BBC News, "45 percent are women and children. … Among the killed, 25 percent of the killed are children and women. … So these numbers are contradictory to everything Israel has said."

Forty-five Egyptian doctors are trying to join Gilbert, but the border remains closed.

Israel Keeps Eye on Hezbollah

"People are dying now because of the lack of supplies. We have all the operating rooms full. Yesterday, we were operating two patients in one operating room. The patients have to wait a long time for surgery and they are dying waiting for surgery. This is a complete disaster," Gilbert said.

On Israel's northern border there was more cause for concern. The Lebanese press reported that Israeli jets had strayed into Lebanon's airspace. Israel's Defense Forces did not comment on the reports though Defense Minister Ehud Barak, when he announced the ground invasion Saturday night, said the country was keeping a watchful eye on its northern border where Israel fought a war with Hezbollah in 2006.

And Lebanon's Al Hayat newspaper reports that Hezbollah forces have been put on the highest state of alert. Hezbollah leader Hassan Nasrallah has been giving fiery speeches daily in Beirut but has so far not directed his fighters to conduct attacks along Israel's northern border.

Palestinian Parliamentarian Hanan Ashrawi says now that Israel has committed ground forces, it has the tougher job. It must get Hamas to relent, otherwise, "it seems to me Hamas has to survive, that's all it has to do; not to surrender, not to wave a white flag and then it will present itself as being the victor."

Sami Zyara contributed to the reporting of this story from Gaza; Simon McGregor-Wood from the Gaza-Israel border; and Nasser Atta, Matthew McGarry, Bruno Nota, Dana Savir and Franco Shlomo from Jerusalem.