TEL AVIV/ GAZA STRIP — After more than 48 hours of the type of intense, door-to-door fighting unseen in Israel for decades, the country's military has retaken control of all the communities around Gaza that gunmen from Hamas had infiltrated, the Israeli military said.

Israeli forces are currently conducting "wide-scale strikes" on several "strategic" centers in Gaza belonging to Hamas, the Israel Defense Forces (IDF) said in a statement Monday.

The militant group began its assault early Saturday morning, firing rockets into Israel and then sending gunmen over the border from Gaza.

More than 700 people were killed, including foreign nationals and dual citizens from Brazil, France, Mexico, Nepal, Thailand, Ukraine, the United Kingdom and the United States.

Many of those killed were young civilians who were attending an all-night rave. Israeli rescue workers said they found at least 260 bodies at the festival site.

Hamas, which is designated as a terrorist group by the United States and the European Union, claims to have taken more than 100 people hostage, including high-ranking army officers.

Young children and elderly Israelis are among those who were kidnapped and later swept across the border back into Gaza, according to Israeli officials. Foreigners, including nine US citizens, have been killed, and some are being held captive as well

Israel responded quickly to the attack by launching heavy airstrikes targeting Hamas in Gaza and formally declaring war on the militant group on Sunday.

Palestinian authorities said at least 560 people have been killed in the strikes, which continued overnight, and that residential buildings and mosques had been flattened.

The United Nations Relief and Works Agency (UNRWA) said nearly 74,000 people had been displaced and were taking shelter in their schools.

Hamas responded to the airstrikes by firing another volley of rockets into Israel, including 120 toward Ashdod and Ashkelon. The salvo set off sirens in Jerusalem and Tel Aviv as well.

Israel's defense minister said Monday that he had given the order for a "complete siege" of the enclave, cutting it off from electricity, food and water.

The decision will almost certainly complicate the lives of those living in Gaza, a small and impoverished enclave whose borders are effectively controlled by the Israeli military.

The siege announcement is the latest indication of just how severe Israel's military response will be. The Israeli government formally declared war on Hamas on Sunday, setting the stage for a major response that could include the first full occupation of Gaza since 2005, when Israel unilaterally withdrew.

Former caretaker Prime Minister Yair Lapid said a ground incursion was not off the table, but that it must consider the fate of the dozens of hostages taken into Gaza.

Meanwhile, ordinary Palestinians say they have nowhere to go to escape as Israel retaliates against Hamas.

Following vows of retribution from Israeli Prime Minister Benjamin Netanyahu, who declared that his country was at war. On Monday, Defense Minister Yoav Gallant ordered a “complete siege” of Gaza, cutting off electricity, food, fuel and water to the enclave.

No strangers to war with Israel, many Gazans are sheltering in their homes, with the vast majority lacking access to bunkers. The territory is one of the most densely populated places on earth, where some 2 million people live in an area of 140 square miles.

Those who venture out do so only to complete essential errands, or to look for their missing loved ones in the carnage of Israeli strikes. The streets are damaged and covered with rubble, and the air smells of dust and gunpowder.

The IDF on Sunday said it was focused on taking control of the Gaza Strip, and urged civilians there to leave residential areas near the border immediately for their safety as Israeli military operations continued to target Hamas.

But most Gazans have no way of fleeing the besieged enclave. All crossings out of the territory are shut, with the exception of the tightly controlled Rafah crossing with Egypt.

Also, services at the only functioning hospital in Gaza's Beit Hanoun neighborhood have been suspended due to continuous Israeli airstrikes, the Palestinian Ministry of Health in Gaza said Monday.

Extensive damage caused by continuous Israeli airstrikes blocked medical teams’ ability to enter or exit the building, the Health Ministry said.

The loud booms in Tel Aviv have been near constant on Monday. One after another, the bangs reverberate throughout the city, as Israel’s Iron Dome air defense system keeps intercepting rockets and its military launches strikes against the Gaza Strip.

People in the city don’t just hear these bangs. Sometimes, they can feel them too.

The Israel Defense Forces (IDF) said dozens of its fighter jets struck several "targets" in the Al-Furqan area in Gaza earlier on Monday.

The area "serves as a hub for the Hamas organization in the Gaza Strip, from which many operations against Israel were launched, including over the last two days," the IDF claimed in a statement.

In another development, 300 Mexican citizens in Israel have signed up to leave the country, Mexico's President Andrés Manuel López Obrador said Monday, noting the country would send two aircraft to carry out evacuations.

The majority of Mexicans in Israel are there for tourism and religious purposes, the president said. The government decided to send the aircraft — one will go in the morning, the other in the afternoon — due to commercial flight cancelations.

Several airlines have suspended flights to and from Israel, as intense fighting rages between Israeli forces and Hamas:

American Airlines, has canceled all flights to and from Tel Aviv. Norwegian Air has canceled all flights from Copenhagen and Stockholm to Tel Aviv until Sunday.

Korean Air, the only South Korean airline that operates direct flights between Incheon and Tel Aviv, canceled its Monday flight — but said it would operate a return flight from Tel Aviv to Incheon, to bring people home.

Air India has also suspended flights to and from Tel Aviv until Oct. 14, citing the safety of its passengers and crew. Hong Kong carrier Cathay Pacific also canceled its Tuesday flight to and from Tel Aviv, saying it would closely monitor the situation.

Other major carriers, including United Airlines and Delta Air Lines have also seen flight disruptions and cancelations due to the conflict. — CNN