At least 26 people were killed and 93 wounded when Israeli airstrikes hit a mosque and a school sheltering displaced people in the Gaza Strip early on Sunday, the Hamas-run Gaza government media office said.

Israel's war in Gaza, launched after the October 7 attacks and aimed at eliminating Hamas, another Iran-backed group, has killed nearly 42,000 people, Palestinian authorities say. The coastal enclave lies in ruins.

The Israeli military's airstrikes in the Gaza Strip early Sunday signalled that it was stepping up operations in the enclave as it pressed on with its campaign against Hezbollah in Lebanon.

The apparent escalation in Israeli military activity — against Hamas in Gaza and Hezbollah — comes amid rising concern over a broadening war in West Asia on the eve of the anniversary of Hamas’s October 7 attack on Israel. That attack prompted Israel to bombard and invade Gaza to fight Hamas.

Early on Sunday, the Israeli military issued evacuation orders for the vast majority of northern Gaza, saying this was in preparation for “a new phase” in the war. That came hours after Israeli warplanes attacked Jabaliya, in the northern part of the enclave. The Israeli military said it had surrounded an area where it had identified Hamas fighters and “efforts by Hamas to rebuild its operational capabilities”.

The military also said that it had struck a mosque and a school-turned-shelter in the central Gaza city of Deir al Balah overnight. It described the two locations as Hamas “command and control centres” nestled among civilians, without providing evidence of its claims. The Palestinian health ministry in Gaza said 26 Palestinians had been killed and dozens more were wounded.

In recent weeks, Israel has intensified attacks against Hamas’s allies, like Hezbollah in Lebanon. Iran, which supports both Hezbollah and Hamas, launched a barrage of missiles at Israel last week in retaliation for assassinations — and Israel has vowed to respond.

Jabaliya is home to a densely populated refugee camp dating back to the 1948 war surrounding Israel’s creation. The Israeli military circulated photos and video footage showing a column of tanks heading toward the area.

Israeli forces encircled Jabaliya as warplanes struck militant sites inside, the military said. Over the course of the war, Israel has carried out several large operations there, only to see militants regroup.

Israel reiterated its call, from the opening weeks of the war, for the complete evacuation of northern Gaza. Up to 300,000 people are estimated to have remained in the heavily destroyed north after earlier Israeli warnings that sent around a million fleeing to the south.

“We are in a new phase of the war,” the military said in leaflets dropped over the area. “These areas are considered dangerous combat zones.”

Palestinian residents reported heavy Israeli strikes across northern Gaza. The Civil Defence — first responders who operate under the Hamas-run government — said several homes and buildings had been hit and they were not able to reach them because of the bombardment.

Residents posted about the airstrikes and mourned their relatives on social media. Imad Alarabid said in a Facebook post that an airstrike on his home in Jabaliya killed a dozen family members, including his parents. Saeed Abu Elaish, a health ministry medic, said he was wounded and bleeding. “Pray for us,” he wrote on Facebook.

Hassan Hamd, a freelance TV journalist whose footage had aired on Al Jazeera and other networks, was killed in artillery shelling on his home in Jabaliya. Anas al-Sharif, an Al Jazeera reporter in northern Gaza, confirmed his death.