Gaza Strip (AP) -- The Israeli military ordered more evacuations in southern Gaza early Sunday after a deadly airstrike on a school-turned-shelter in the north killed at least 80 Palestinians, according to local health authorities. Israel said it targeted a militant command post, killing 19 fighters.

Israel has repeatedly ordered mass evacuations as its troops have returned to heavily destroyed areas where they had previously battled Palestinian militants. The vast majority of Gaza's population of 2.3 million people have been displaced by the 10-month-old war , often multiple times.

Hundreds of thousands have crammed into squalid tent camps with few public services or sought shelter in schools like the one struck on Saturday. Palestinians say nowhere in the besieged territory feels safe.

The latest evacuation orders apply to areas in Khan Younis, including part of an Israeli-declared humanitarian zone from which the military said rockets had been fired. Israel accuses Hamas and other militants of hiding among civilians and launching attacks from residential areas.

Khan Younis, Gaza’s second-largest city, suffered widespread destruction during an air and ground offensive earlier this year. Tens of thousands fled again last week after an earlier evacuation order.

Hundreds of families carrying their belongings in their arms left their homes and shelters early Sunday, seeking elusive refuge.

“We don’t know where to go,” said Amal Abu Yahia, a mother of three, who had returned to Khan Younis in June to shelter in their severely damaged home. “This is my fourth displacement," said the 42-year-old widow, whose husband was killed when an Israeli airstrike hit their neighbors’ house in March.

She said they went to Muwasi, a sprawling tent camp along the coast, but could not find any space.

Ramadan Issa, a father of five in his 50s, fled Khan Younis with 17 members of his extended family, joining hundreds of people walking toward central Gaza early Sunday.

“Every time we settle in one place and build tents for women and children, the occupation comes and bombs the area," he said, referring to Israel. "This situation is unbearable.”

Gaza's Health Ministry says the Palestinian death toll from the 10-month-old war is approaching 40,000, without saying how many were fighters. Aid groups have struggled to address the staggering humanitarian crisis in the territory, while international experts have warned of famine .

The war began when Hamas-led militants burst through Israel's defenses on Oct. 7 and rampaged through farming communities and army bases near the border, killing some 1,200 people — mostly civilians — and abducting around 250 people.

The United States, Egypt and Qatar have spent months trying to mediate a cease-fire and the return of the roughly 110 remaining hostages , around a third of whom Israeli authorities believe to be deceased. The conflict has meanwhile threatened to trigger a regional war, as Israel has traded fire with Iran and its militant allies across the region .

The strike on Saturday hit a mosque inside a school in Gaza City where thousands of people were sheltering. The Gaza Health Ministry said 80 people were killed and around 50 wounded. The Israeli military disputed the toll and said it killed 19 Hamas and Islamic Jihad militants in a precise strike, releasing what it said were their names and photos.

Hamas and Palestinian activists disputed the military's claims, saying two of the 19 had been killed in earlier strikes and that others were known to be civilians or opponents of Hamas.

Gaza City and the rest of the north have been surrounded by Israeli forces and largely cut off from the world since late last year, and it was not possible to independently confirm the accounts from either side.

The U.N. human rights office says Israel has carried out “systematic attacks on schools,” which have served as shelters since the start of the war, with at least 21 hit since July 4, leaving hundreds dead, including women and children.

European leaders condemned the strike, while the U.S. said it was concerned about the reports of civilian casualties. Vice President Kamala Harris, speaking to reporters traveling with her in Phoenix, Arizona, on Saturday, said: “Yet again, far too many civilians have been killed.”

“We need a hostage deal and we need a cease-fire,” she said. “The deal needs to get done and it needs to get done now.”