DEIR AL-BALAH, Gaza Strip — The Israeli military urged all Palestinians to leave Gaza City and head south Wednesday, pressing ahead with a fresh offensive across the north, south and center of the embattled territory that has killed dozens of people over the past 48 hours.

The stepped-up military activity came as U.S., Egyptian and Qatari mediators met with Israeli officials in the Qatari capital, Doha, for talks seeking a long-elusive cease-fire deal with Gaza’s Hamas in exchange for the release of dozens of Israeli hostages it is holding.

Israel says it is pursuing Hamas fighters that are regrouping in various parts of Gaza nine months into the war.

But heavy strikes in recent days along the length of the territory also could be aimed at putting more pressure on Hamas in the cease-fire talks.

In a visit Wednesday to central Gaza, Israel’s military chief, Lt. Gen. Herzi Halevi, said forces were operating in different ways, in multiple parts of the territory “to carry out a very important mission: pressure. We will continue operating to bring home the hostages.”

Israel informed people in Gaza of the evacuation order by dropping leaflets urging “all those in Gaza City” to take two “safe routes” south to the area around the central town of Deir al-Balah.

Gaza City, it said, will “remain a dangerous combat zone.”

Months ago, Israel ordered residents of northern Gaza, including Gaza City, to flee south, and much of the population left earlier in the war. Large parts of Gaza City and urban areas around it have been flattened or left a shattered landscape by previous Israeli assaults.

The United Nations says about 300,000 Palestinians have remained in the hard-hit north, with the bulk of those said to be in Gaza City.

Most of Gaza’s 2.3 million people are crammed into squalid tent camps in central and southern Gaza.

Israeli troops have pushed into parts of Gaza City in recent days, triggering the flight of thousands of Palestinians trying to escape shelling and airstrikes. This past week, the military ordered Palestinians to evacuate from eastern and central parts of the city.

There was no immediate mass exodus from the city following Wednesday’s order. Many Palestinians have concluded that there is no refuge in war-stricken Gaza.

The military, meanwhile, said it wrapped up an operation launched late last month in the Gaza City neighborhood of Shijaiyah, where it killed dozens of combatants and destroyed eight underground tunnels.

Wednesday’s evacuation order came after a series of deadly strikes over the past two days in other parts of the territory. Israeli bombardment early Wednesday hit four houses in Deir al-Balah and the nearby Nuseirat refugee camp, killing 20 Palestinians.

Among the dead were six children and three women, according to officials at al-Aqsa Martyrs Hospital, where the casualties were taken. The house hit in Deir al-Balah was inside the “humanitarian safe zone” where Israel has told Palestinians to flee for refuge.

The overnight bombardment came hours after Israeli warplanes struck the entrance of a school sheltering displaced families outside the southern city of Khan Younis. The toll from the strike rose to 31 people killed, including eight children, and more than 50 wounded, officials at the nearby Nasser Hospital said Wednesday.

Footage aired by Al Jazeera television showed kids playing soccer in the school’s yard when a sudden boom shook the area, prompting shouts of “a strike, a strike!”

The Israeli army said the airstrike near the school and reports of civilian casualties were under review. It claimed it was targeting a Hamas fighter who took part in the Oct. 7 attack on Israel that triggered the war, though it provided no evidence. The military blames civilian deaths on Hamas because the combatants fight in dense, urban areas. But the army rarely comments on what it is targeting in individual strikes, which often kill women and children.

In nine months of bombardment and offensives in Gaza, Israel has killed more than 38,200 people and wounded more than 88,000, according to the territory’s Health Ministry, which does not distinguish between combatants and civilians in its count. Nearly the entire population has been driven from their homes. Many have been displaced multiple times.

During the Oct. 7 raid, militants killed some 1,200 people in southern Israel, most of them civilians, according to Israeli authorities. The combatants took roughly 250 people hostage. About 120 are still in captivity, with about a third said to be dead.