The health ministry in Hamas-run Gaza said an Israeli strike on a school killed 30 people on Saturday, after a days-long military operation further south left around 170 dead, according to emergency services.
The latest strike, which Israel said targeted "terrorists", was at least the eighth time since July 6 a school has been hit, leaving a total of more than 100 people dead, based on figures given by the health ministry and a hospital source.
With most of the Gaza Strip's 2.4 million people displaced at least once during the war started by Hamas's October 7 attack, many have sought refuge in school buildings including the one hit on Saturday.
The health ministry reported "30 martyrs and more than 100 wounded" in the strike on Khadija school in the central Deir el-Balah area.
Israel's military said Palestinian militants were using the compound as a "hiding place".
Further south, in the Khan Yunis city area, around 170 people have been killed "and hundreds wounded" in an Israeli operation since Monday, Gaza's civil defence agency said.
It issued the toll after the military warned of new operations in the Khan Yunis area, where troops had earlier recovered the bodies of five Israelis killed during the October 7 attack and held in Gaza since.
Egyptian state-linked media said Egyptian, Qatari and US mediators are to meet with Israeli negotiators in Rome on Sunday in the latest push for a Gaza truce, which critics of Israeli Prime Minister Benjamin Netanyahu have accused him of blocking.
Aid effort 'destabilised'
Israel had warned on Monday that its forces would "forcefully operate" in the Khan Yunis area.
On Saturday, the military ordered residents from more parts of Khan Yunis "to temporarily evacuate to the adjusted humanitarian area in Al-Mawasi" -- the second such change to the declared safe zone within a week.
The United Nations said that by Thursday, more than 180,000 Palestinians had already fled fierce fighting there.
Mahmud Bassal, spokesman for the civil defence agency, told AFP that many people had been displaced again on Saturday as the Israeli operation continued.
But with large parts of Khan Yunis "not suitable for living" and "no other options available", civilians have struggled to find safety, he said.
"Where will these residents go?"
The evacuation orders and "intensified hostilities" have "significantly destabilised aid operations", the UN said, reporting "dire water, hygiene and sanitation conditions" in the Palestinian territory.
Khan Yunis was left devastated after heavy fighting early in the year but the military withdrew in April saying it had "concluded its mission" there.
Now it has returned in force. On Wednesday the military said troops carried out an operation in Khan Yunis and retrieved the five bodies.
Israel said on Friday that its forces had "eliminated approximately 100" militants in Khan Yunis during the week.
Rome talks
The October 7 attack on southern Israel resulted in the deaths of 1,197 people, mostly civilians, according to an AFP tally based on official Israeli figures.
Militants also seized 251 hostages, 111 of whom are still held captive in Gaza, including 39 the military says are dead.
Israel's retaliatory military campaign in Gaza has killed at least 39,258 people, according to Gaza's health ministry, which does not provide details of civilian and militant deaths.
Its latest toll on Saturday included 83 deaths over the previous 48 hours.
In the southern city of Rafah, medics said four people were killed in an air strike on a house.
Israel's military said troops had targeted "military infrastructure sites" in the Rafah area.
Al-Qahera News, which has links to Egyptian intelligence, reported on Friday that talks "to reach agreement on a truce in Gaza" would take place in Rome on Sunday. US media outlet Axios separately reported that CIA Director Bill Burns was expected to attend.
The latest mediation efforts have focused on a ceasefire and hostage release accompanied by the freeing of Palestinian prisoners held by Israel.
In a meeting in Washington on Thursday, US President Joe Biden called on Netanyahu to "finalise" a deal and "reach a durable end to the war in Gaza", the White House said.