The IDF said it's carried out 10,000 airstrikes in the Gaza Strip.
The temporary cease-fire between Hamas and Israel ended early Friday, and Israel has resumed its bombardment of Gaza.
The end of the cease-fire came after Hamas freed over 100 of the more than 200 people its militants took hostage during the Oct. 7 surprise attack on Israel. In exchange, Israel released more than 200 Palestinians from Israeli prisons.
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The latest outbreak of war between Israel and Hamas, the Palestinian militant group that governs the Gaza Strip, has passed the four-month mark.
In the Gaza Strip, at least 30,228 people have been killed and 71,377 others have been wounded by Israeli forces since Oct. 7, according to Gaza's Hamas-controlled Ministry of Health.
In Israel, at least 1,200 people have been killed and 6,900 others have been injured by Hamas and other Palestinian militants since Oct. 7, according to the Israel Defense Forces.
There has also been a surge in violence in the Israeli-occupied West Bank. Israeli forces have killed at least 395 people in the territory since Oct. 7, according to the Palestinian Ministry of Health.
The ongoing war began after Hamas-led militants launched an unprecedented incursion into southern Israel from neighboring Gaza via land, sea and air. Scores of people were killed while more than 200 others were taken hostage, according to Israeli authorities. The Israeli military subsequently launched retaliatory airstrikes followed by a ground invasion of Gaza, a 140-square-mile territory where more than 2 million Palestinians have lived under a blockade imposed by Israel and supported by Egypt since Hamas came to power in 2007. Gaza, unlike Israel, has no air raid sirens or bomb shelters.
The process of transferring a fifth group of Hamas-held hostages has begun, a source in the Israeli Prime Minister's Office with direct knowledge of the operation told ABC News on Tuesday evening.
It was unclear how long the process would take to be completed. It took about an hour on Monday night for hostages to be transferred from the Gaza Strip back to Israel.
-ABC News' Jordana Miller and Morgan Winsor
All 50 women and children hostages who were in the original swap agreement have been released, Israeli Prime Minister Benjamin Netanyahu said.
"We are obliged to complete this outline and bring about the release of all our abductees -- women and children and later, everyone -- without exception," he said.
The Israel Defense Forces "is prepared to continue fighting" in the Gaza Strip and is "using the days of the pause as part of the framework to learn, strengthen our readiness and approve future operational plans," according to IDF Chief of Staff Lt. Gen. Herzi Halevi.
"The return of the hostages is a bright light for us all," Halevi said in a statement on Tuesday. "It is also further evidence of the results of significant military pressure and resolute ground operations, which created the conditions for the return of our civilians home."
Halevi vowed "to apply the same strength" if needed in northern Israel, where he said some residents have been evacuated from their homes amid clashes along the border between Israeli forces and Lebanese militant group Hezbollah.
"The IDF's ground operations in Gaza City, a dense and complex area, aim to achieve a worthy and necessary goal," he said. "We know, if required, how to apply the same strength in the north, in order to return you safely to your communities, cities and this beautiful and important region of the country."
-ABC News' Morgan Winsor
About 1.8 million Gaza residents -- over 80% of the population -- are now displaced, according to the United Nations.
Nearly 1.1 million of those displaced residents have sought shelter from the United Nations Relief and Works Agency for Palestine Refugees in the Near East.
But the shelters are so overcrowded that they may have just one toilet for every 125 people and one shower for every 700 people, the U.N. said.
Instead of staying at the shelters, many residents are instead camping at the sites of their destroyed homes, the U.N. said.
