Death Toll Nears 1,300 As War Rages After Hamas' Attack On Israel

Air raid sirens blared in the Israeli capital again Monday morning as Palestinian militants fired more missiles at the Jewish state and the death toll on both sides soared over 1,300, with nine Americans among the dead.

Explosions rang out as Israel's Iron Dome air defense system brought down some of the rockets, but there was no immediate word on how many might have slipped through. 

The latest salvo of rockets, claimed by Hamas' al-Qassam Brigades military unit, came after Israel said it had struck hundreds of Hamas targets in the Gaza Strip overnight and as four Israeli combat divisions were deployed to the country's south. Some 100,000 Israeli reservists were called up to fight as battles with Hamas militants continued. 

The Israel Defense Forces (IDF) said "fighter jets and helicopters, aircraft and artillery struck over 500 Hamas and Islamic Jihad terrorist targets in the Gaza Strip" Sunday night and Monday morning, claiming to have destroyed tunnels and at least seven "Hamas command centers" in the blockaded Palestinian territory. The IDF said it also struck a command center used by Islamic Jihad, another Iran-backed terror group based in the Hamas-run Gaza Strip. 

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"It's taking more time than we expected to get things back into a defensive security posture," Israeli military spokesperson Lt. Col. Richard Hecht told journalists Monday morning, acknowledging the ongoing battles in southern Israel three days after Hamas launched its unprecedented attack on the Jewish state.

Death toll mounts as Israel bolsters Gaza blockade

Officials said the Israeli death toll from Hamas' surprise attack stood at 700 Monday morning, but it was expected to continue rising. More than 250 of the dead were people who had been attending a music festival near the border with Gaza when the attack took place. 

At least nine U.S. nationals were among the dead, a spokesperson for the U.S. National Security Council told CBS News Monday morning. An undetermined number of Americans remained missing.

Israel made it clear that it wants vengeance, and in the Gaza Strip, retribution was falling from the sky. The airstrikes had killed more than 590 people as of Monday morning, including at least 91 children, according to the Gaza Ministry of Health. It said some 2,900 more were wounded in the strikes.

In the coming days, Israel is expected to launch a ground incursion into Gaza, a small, densely packed region sandwiched between the Mediterranean Sea to the west and Israel to the north and east. 

Israeli Defense Minister Yoav Gallant said Monday that he'd ordered a tightening of the Gaza blockade: "Nothing is allowed in or out. There will be no fuel, electricity or food supplies," he said in a statement. "We fight animals in human form and proceed accordingly."

CBS News' Marwan al-Ghoul reported from Gaza City that the Israeli airstrikes had been relentless since Saturday. While Israel insists it is targeting Hamas and other terror groups, it has long accused those militants of positioning both fighters and weapons in or near civilian infrastructure.

Houses, apartment buildings and mosques were all among the targets hit overnight, most of them without prior warning, al-Ghoul said.

"I could not sleep last night as the planes bombed the mosque nearby, causing casualties and breaking the windows of my house," Samar Alyan, who lives in the sprawling al-Shati refugee camp just west of Gaza City, told CBS News.

"We do not know what fate has in store for us," she said. "Israel retaliates on civilians."

The camp is home to some 150,000 refugees.

In the center of Gaza City, schools run by the U.N.'s humanitarian agency in the Palestinian territories, UNRWA, were full of displaced people looking for any safety they could find.

Israeli infrastructure minister Israel Katz said in a tweet that he had "ordered to immediately cut off the water supply from Israel to Gaza," adding that "electricity and fuel were cut off yesterday" to the Palestinian territory, which is home to some 2 million people.

Israel has been locked in a cycle of violence with Palestinian militant groups for decades, but what happened on Saturday was unprecedented. Hundreds of Hamas militants broke through the steel and concrete barrier that Israel has used for decades to contain Palestinians inside Gaza.

They stormed into Israel by land, sea and even on paragliders as waves of rockets — more than 3,000 of them — were unleashed on Israeli towns and cities.

The gunmen from the group, which has long been designated a terrorist organization by the U.S. and Israel, went on a rampage, slaughtering civilians in the streets, engaging Israeli security forces with deadly effect, and kidnapping hostages including women, children and the elderly. 

Some of them were paraded through the streets of Gaza — human trophies that Hamas knows it can use as leverage against its enemy.

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One of the captives is Noa Argamani, a university student who was hauled away on the back of a motorcycle as she screamed for help.

"She is an amazing person, a sweet child," her father Yaacov told CBS News. "I cannot believe it."

The shocked father said he wanted the Israeli government to rescue his daughter, but "only by peaceful measures."

"We need to act with sensitivity," he said. "They [Palestinians] also have mothers who are crying, the same as it is for us."

"Seems like Israel had no clue"

For many in Israel, the question burning Monday morning was how the country's intelligence agencies could have failed to detect and disrupt planning for such a significant Hamas assault.

"It seems like Israel had no clue," former Israeli intelligence officer Gonen Ben Itzhak, who used to recruit spies to infiltrate Hamas, told CBS News. He said Israel — distracted by simmering violence in the other Palestinian territory, the Israeli-occupied West Bank, where it's been protecting Israeli settlers — let down its guard in Gaza.

"I won't be surprised if they will start to even kill some of the hostages on camera," he said, predicting that Hamas would try to force the Israeli government to negotiate. 

But Israeli leaders and military officials weren't discussing any negotiations Monday morning.

With some people calling the attack Israel's 9/11, military spokesman Lt. Col. Jonathan Conricus said the objective was "to make sure that at the end of this war, Hamas will no longer have any military capabilities to threaten Israeli civilians with, and in addition to that, we also need to make sure Hamas will not govern the Gaza Strip."

CBS News' Erin Lyall and Duarte Dias contributed to this report.