A deadly strike hit a school turned shelter in southern Gaza on Tuesday as Israeli forces in the war-ravaged territory's main city pushed on with a major offensive that has again displaced Palestinians.
A hospital source in Khan Yunis in southern Gaza said at least 29 people were killed when the school was hit in nearby Abasan.
The Israeli military said its air force had carried out a strike in the area targeting a "terrorist" and would review the incident.
Three previous Israeli strikes since Saturday on schools across Gaza used by displaced Palestinians have killed a total of at least 20 people, according to officials and rescuers.
In the northern Gaza Strip, Israeli troops, tanks and fighter jets swooped on Gaza City on the eve of new contacts in Qatar aiming for an eventual hostage-prisoner exchange and a truce in the war, raging into its 10th month.
CIA director William Burns and Israel's Mossad chief David Barnea are due to travel to Qatar on Wednesday, after Burns held talks with Egypt's President Abdel Fattah al-Sisi in Cairo.
Hamas, whose October 7 attack triggered the war, has softened a key demand and accused Israeli Prime Minister Benjamin Netanyahu of deliberately escalating fighting to thwart an agreement.
The Islamist group's Qatar-based political chief Ismail Haniyeh said he had warned mediators that the "catastrophic consequences" of the latest battles could "reset the negotiation process".
Hamas's armed wing, the Ezzedine Al-Qassam Brigades, described the latest fighting in Gaza City as "the most intense in months".
The United Nations said tens of thousands of civilians have been affected by the surge in fighting since the first of three evacuation orders for Gaza City was declared on June 27.
Philippe Lazzarini, head of the UN agency for Palestinian refugees UNRWA, said that "we have around 350,000 people again on the road" but "basically, there is absolutely no safe space in Gaza".
- 'Starvation campaign' -
After almost two weeks of battles in Gaza City's eastern Shujaiya district, Israeli forces have extended the fighting further into the city's east, west and south.
Residents told AFP they saw helicopter strikes, "explosions, and numerous gun battles" in the city's southwest.
Elsewhere in Gaza, witnesses reported artillery shelling near the central Nuseirat refugee camp and west of Rafah, in the territory's south.
Israel's military said its air and ground forces were pursuing Palestinian militants in Gaza City, six months after it said it had dismantled Hamas's "military framework" in the territory's north.
The UN Human Rights Office said it was "appalled" at the way civilians, many of whom have been displaced multiple times, have been ordered to head to areas where "military operations are ongoing and where civilians continue to be killed and injured".
Thousands were seen marching down dusty roads past bombed-out buildings, with mothers carrying babies and others packing belongings onto donkey carts.
Independent UN rights experts accused Israel of carrying out a "targeted starvation campaign" that has resulted in the deaths of Gazan children and constituted "a form of genocidal violence".
"Thirty-four Palestinians have died from malnutrition since October 7, the majority being children," said the experts, who are appointed by the UN Human Rights Council but who do not speak on behalf of the United Nations.
Israel's mission to the UN in Geneva accused the panel's members of "spreading misinformation" and "supporting Hamas propaganda".
- 'Only lifeline' -
Yussef Jaber, 24, said there was hardly any food left in northern Gaza, lamenting "a life of shame and humiliation".
"There is nothing for us except some flour and tinned goods that make us sick," he said. "We have no vegetables to cook or meat."
More than nine months of war have shuttered many hospitals across Gaza, and on Tuesday the Palestinian Red Crescent said all of its facilities in the Gaza City area were out of service.
Jagan Chapagain, head of the International Federation of Red Cross and Red Crescent Societies, said on social media platform X that "the closure of these vital medical facilities exacerbates an already dire healthcare system".
"These clinics and medical points are often the only lifeline for many civilians."
Hamas's October 7 attack on southern Israel resulted in the deaths of 1,195 people, mostly civilians, according to an AFP tally based on Israeli figures.
The militants seized 251 hostages, 116 of whom remain in Gaza, including 42 the military says are dead.
Israel responded with a military offensive that has killed at least 38,243 people in Gaza, also mostly civilians, according to figures from the Hamas-run territory's health ministry.
Hamas has signalled that it would drop its insistence on a "complete" ceasefire -- which Israel has repeatedly rejected -- as a condition for starting truce talks, mediated by Qatar and Egypt with support from the United States.
Netanyahu's office has set out conditions, including that "any deal will allow Israel to return and fight until all the goals of the war are achieved".
- Conflict with Hezbollah -
As the Gaza war has raged on, Israel has also exchanged regular cross-border fire with Lebanon's Hezbollah, allies of Hamas, heightening fears of an all-out war.
Hezbollah on Tuesday released a video showing aerial surveillance footage it said was taken over intelligence and military positions in the Israeli-annexed Syrian Golan Heights.
Rocket fire on Tuesday killed two Israelis in the Golan Heights, police said.
It came after an Israeli strike last week killed a senior Hezbollah commander, prompting retaliatory barrages of rockets and drones.
Israeli Foreign Minister Israel Katz, on X, told Hezbollah leader Hassan Nasrallah to "stop the threats and violence", and "withdraw" forces from the border area, in line with UN Security Council Resolution 1701 that ended their latest major war in 2006.
If a full-blown conflict breaks out, Israel's top diplomat said Nasrallah "will be considered the destroyer of Lebanon".