Updated: 4:40 p.m.
Israeli forces launched unrelenting airstrikes into the densely populated Gaza Strip on Monday with the aim of rooting out Hamas forces, Israeli Defense Forces spokesman Jonathan Conricus said Monday night local time.
The airstrikes continued for 10 hours Monday, as Isreali forces react so "Hamas won't be able to strike Israeli civilians ever again," Conricus said his video update.
In an address to the country, Israeli Prime Minister Benjamin Netanyahu vowed that the military offensive is just beginning.
"We have only started striking Hamas," he said. "What we will do to our enemies in the coming days will reverberate with them for generations."
Grow the Future of Public Media
MPR News is supported by Members. Gifts from individuals power everything you find here. Make a gift of any amount today to become a Member!
As Israeli forces dial up their response, Hamas threatened the lives of civilian hostages if Israel bombs homes of women, children and elderly leaders living in Gaza without warning, according to a message from the military wing of the group issued late Monday. Hamas reportedly holds scores of men, women and children.
In audio released through Hamas Telegram channels and other mediums, Ezzedin al-Qassam Brigades said the group will execute a civilian hostage and will be compelled to release the sound and images of that execution.
"We hold, before the world, the Zionist enemy responsible for this decision. The ball is in their court from this moment," said the group's spokesman, who goes by the name Abu Obeida.
The unprecedented violence effecting Palestinians and Israelis comes after a Saturday morning attack by Hamas. Gunmen for the group infiltrated Israel by sea, land and air entering homes, killing civilians and capturing hostages of all ages. A rave near the border with Gaza was also attacked.
Conricus called it "by far the worst day in Israeli history."
There are 2,300 wounded and 700 dead from these attacks, according to the IDF. Most of the victims are civilians.
In retaliation for the attacks from Hamas, Israel has focused its attacks on the Gaza Strip, home to 2.3 million Palestinians, most of them refugees.
Conricus said Israeli forces have regained full control of all the southern territory where there were Palestinian gunmen, three days after the initial attack from Hamas. He said 300,000 reservists have been mobilized in southern and northern Israel.
Officials for the Health Ministry in Gaza said Monday that more than 680 people have been killed in Israeli strikes and more than 3,700 others wounded, according to the Associated Press.
Nine U.S. citizens have also died, officials from the U.S. State Department and the National Security Council confirmed Monday.
Three days since the conflict began, there are still a number of unaccounted-for U.S. citizens that the State Department says it's working with its Israeli partners to help find, according to spokesman Matthew Miller. He did not provide any details about the victims or how they died.
"We extend our deepest condolences to the victims and to the families of all those affected. We continue to monitor the situation closely and remain in touch with our Israeli partners and the local authorities," Miller said in an emailed statement.
Civilians wait to hear news of loved ones
There are still a lot of unanswered questions regarding the status of victims and hostages.
Israelis fear that the attack at the rave left at least 260 people killed.
NPR's Daniel Estrin spoke with Ahuva Maisel, whose 21-year-old daughter named Adi was at that festival and is still missing.
"I don't know if she's alive. I don't know if she's dead. I don't know if she's hurt. I know nothing. I don't know if somebody captured her," Maisel said.
She said she's received phone calls from people purporting to be from Hamas.
"And they say that they have my daughter, my beautiful daughter, and I hear screaming of girls," Maisel said. She is unsure if the calls are fake or not.
Other Israelis have said they've received videos of loved ones captive inside Gaza.
Israel said as part of its full siege of Gaza that it would cut off fuel, electricity and food supplies into the area. In announcing the complete siege, Israel's Defense Minister Yoav Gallant said: "We are fighting human animals and we will act accordingly."
Eman Abou Saeid, a woman in Gaza reached by NPR by phone on Monday, said she had just been told her cousin was killed in an Israeli airstrike. She said he was a civilian who leaves behind a wife and five children.
She said that the images of Israeli civilians being killed and taken hostage are disturbing, something many do not want to see. But she said this kind of reaction was "expected."
"We don't like to see images like that, but it's a fight," Saeid said. "It's a reaction for what Gazans here living since 2006 and since the occupation started, from 1948, and no one just caring about Gaza."
Hamas says Israeli airstrikes on Gaza overnight and into Monday morning killed four hostages and their captors from its military wing. The claim could not be verified.
The group released an image of one of the alleged hostages killed in the airstrike, a 19-year-old Israeli whom Hamas identified by name and described as an Israeli soldier. The image shows him seated on the ground, with his hands behind his head and alive at that time.
U.N. demands aid to be allowed into Gaza
U.N. Secretary-General António Guterres condemned the Hamas attacks on Israel but similarly criticized the continued Israeli air strikes, as well as the plans for an all-out siege of the Gaza Strip.
The situation for Gaza's residents is critical, with nearly all unable to leave the small coastal enclave due to a 16-year blockade imposed by Israel and Egypt.
“The humanitarian situation in Gaza was extremely dire before these hostilities; now it will only deteriorate exponentially. Medical equipment, food, fuel and other humanitarian supplies are desperately needed, along with access for humanitarian personnel,” he said in remarks to the press.
Guterres said two UNRWA schools sheltering displaced families in Gaza were hit by air strikes. And as heavy airstrikes continue, some 137,000 people are sheltering in UNRWA facilities.
He continued, “It's time to end this vicious circle of bloodshed, hatred and polarization. Israel must see its legitimate needs for security materialized – and Palestinians must see a clear perspective for the establishment of their own state realized.”
Tensions rise in neighboring Lebanon
Israel's military said Monday that its forces killed several militants who had infiltrated from the northern border with Lebanon, and that Israeli combat helicopters attacked in the area soon after.
The Palestinian Islamic Jihad's armed wing, Al-Quds Brigades, claimed responsibility for an attempted infiltration into Israel from Lebanon.
The roads in south Lebanon were overwhelmed Monday night with the traffic of civilians fleeing northwards toward the capital, Beirut. Schools have been closed in the south of the country, and, as civilians flee, hundreds of ambulances are being sent to the area.
Aya Batrawy reported from Tel Aviv, Israel; Jaclyn Diaz from Washington, D.C.
Michele Kelemen and Tamara Keith contributed to this report from Washington.
Copyright 2023 NPR. To see more, visit https://www.npr.org.