Dozens of Palestinians have been killed in Israeli attacks in southern Gaza, health officials said, as the UN rights chief warned that the “darkest moment” of Israel’s assault on Gaza was unfolding in the north of the besieged territory.

Women and children were among at least 38 people killed in Israeli air attacks that hit several houses in Khan Younis on Friday, health authorities said.

Al Jazeera’s Tareq Abu Azzoum, reporting from central Gaza’s Deir el-Balah, said images showing the scene of the attack in Khan Younis “are disturbing, with many bodies lying on the ground in Nasser Hospital while parents and relatives bid farewell to the victims who have been transferred for burial.”

Ahmed Sobh recounted how his cousin had screamed, “Help me, help me”.

“We ran and found her children, a boy and a girl, martyred. Her son was lying under the concrete column, it took us 1.5 hours to get him out,” he told the Reuters news agency.

Ahmed al-Farra described digging through rubble to rescue relatives including his mother, adding he had lost 15 members of his extended family during the air strikes.

“As I was trying to dig [my mother] out I looked at this wall and saw a tank aiming at me. I was thinking, ‘Shall I dig or shall I watch the tank,’ what shall I do? I dug her out full of fear. Everyone was doing the same, digging in fear,” he said.

Israeli army strikes across the Gaza Strip have killed at least 72 people since Thursday night, health officials said.

The latest attacks include strikes on three houses in northern Gaza’s Beit Lahiya, where 25 people were killed and dozens more were wounded, medics said.

Later on Friday, an Israeli air strike killed nine people in the Shati refugee camp in Gaza City.

More than 42,000 people have been killed since Israel launched its assault on Gaza in October 2023, according to Palestinian health officials.

As Israel continued its bombardment across the territory, the UN rights chief warned that its offensive in northern Gaza could include “atrocity crimes”.

Israeli forces launched a new offensive in northern Gaza more than two weeks ago. Some 400,000 people are trapped in the area – mainly in Jabalia, Beit Hanoon, and Beit Lahiya.

Gaza’s Government Media Office said at least 770 Palestinians have been killed and 1,000 others wounded in the assault, which entered its 21st day on Friday. Israeli forces have also besieged the Kamal Adwan Hospital, a day after tanks shelled the facility.

Volker Turk, the UN high commissioner for human rights, warned on Friday that Israel’s actions in northern Gaza “risk emptying the area of all Palestinians” and that “we are facing what could amount to atrocity crimes.”

Turk decried “nonstop” bombing in northern Gaza and said that “the Israeli military has ordered hundreds of thousands to move, with no guarantees of return. But there is no safe way to leave.”

In a statement, he said that there were “more than 150,000 people are reportedly dead, wounded or missing in Gaza” since the war there began just more than a year ago.

“Unimaginably, the situation is getting worse by the day,” he said.

“My gravest fear is, given the intensity, breadth, scale and blatant nature of the Israeli operation currently under way in North Gaza, that number will rise dramatically.”

Turk called on the world’s leaders to act, stressing that all states are obligated under the Geneva Conventions to ensure respect for international humanitarian law.

His statement stressed the urgency of the situation, warning that “today the darkest moment of the Gaza conflict is unfolding in the north of the Strip, where the Israeli military is effectively subjecting an entire population to bombing, siege and risk of starvation”.

The UN rights chief cautioned that there was “extremely limited access to this part of Gaza, [and] next to no aid has reached the area in weeks, with unlawful restrictions remaining”.

“Many are now facing starvation.”

The warning comes as the United States renewed its push for a ceasefire deal between Israel and Hamas.

A Hamas official confirmed to Reuters on Friday that a delegation led by the group’s chief negotiator Khalil al-Hayya arrived in Cairo on Thursday for talks with Egyptian officials.

The official said Hamas was determined any agreement must end the offensive in Gaza, get Israeli forces out of the enclave and achieve a prisoners-for-hostages swap deal.

US and Israeli negotiators will gather in Doha in the coming days to try to restart talks, officials said on Thursday.

Qatar and Egypt have acted as mediators between Israel and Hamas in months of talks that broke down in August without an agreement.