The Israeli army says 24 of its soldiers were killed in Gaza on Monday - the deadliest day for its forces since their ground operation began.
That includes 21 reservists who died in an explosion likely caused by mines that Israeli forces had placed in two buildings to demolish them, the Israel Defense Forces (IDF) said.
It is thought a missile fired by Palestinian armed fighters hit a tank guarding the troops just beforehand.
The IDF is investigating what happened.
According to Gaza's Hamas-run Health Ministry, 195 Palestinians have been killed in the past day.
The IDF's chief spokesman, Rear Admiral Daniel Hagari, said the reservists were killed in central Gaza at around 16:00 (14:00 GMT) on Monday - close to the kibbutz of Kissufim on the Israeli side of the border.
They were involved in an operation to allow residents of southern Israel to safely return to their homes after tens of thousands were evacuated after the Hamas attack on 7 October.
The first funerals for those killed in the explosion have been held at Mount Herzl in a rainy Jerusalem.
Many of the mourners wore military uniforms and the scene was full of blue and white Israeli flags.
Israel's military had already confirmed that three officers were killed in a separate attack in southern Gaza on Monday.
The country's Prime Minister Benjamin Netanyahu said that despite its suffering, his country would push on with its offensive until it had "absolute victory."
Elsewhere in Gaza, there has been fierce fighting by three hospitals in Khan Younis in the south, which is crowded with displaced people.
The IDF announced it has completely encircled the city, which has been the main focus of its ground offensive targeting Hamas.
Israel believes that the group's leaders may be hiding there and that it may also be where some Israeli hostages are being held.
According to the IDF, dozens of local gunmen were killed in its operation and its forces found rockets in rocket launchers ready to fire, as well as tunnel shafts and a large number of weapons.
The Palestinians said that women and children have been killed in the latest fighting in the city.
They added that Israeli blockades and the storming of hospitals since Monday had left the wounded and dead beyond the reach of rescuers.
The dead were being buried inside the grounds of Nasser hospital because it has been unsafe to leave in order to reach the cemetery.
It is said that Israeli forces stormed another hospital, Al-Khair - which is in the al-Mawasi area to the west - and arrested staff.
Israel launched the war with the declared aim of destroying Hamas after waves of its gunmen killed 1,300 people - mostly civilians - and took about 250 others hostage in the unprecedented attack.
According to the IDF website, 217 soldiers have been killed since the beginning of Israel's ground invasion on 27 October out of a total of 552 killed since 7th October.
At least 25,490 people - mainly women and children - have been killed in the Israeli military campaign in Gaza since then, according to the Hamas-run health ministry.