At least 26 people were killed across Gaza as Israeli forces blew up homes, besieged schools and shelters for displaced people on Monday.

The army also deepened its operations in northern Gaza's Jabalia and rounded up people and ordered them to leave the camp, residents and medics said.

Medics at the Indonesian Hospital told Reuters that Israeli troops stormed a school and detained the men before setting the facility ablaze. The fire reached the hospital generators and caused a power outage, they added.

Health officials said they refused orders by the Israeli army, which began a new incursion into the north of the Palestinian territory over two weeks ago, to evacuate the three hospitals in the area or leave the patients unattended.

Troops remained outside the hospital but did not enter, they said. Medics at a second hospital, Kamal Adwan, reported heavy Israeli fire near the hospital at night.

"The army is burning the schools next to the hospital and no one can enter or leave the hospital," said one nurse at the Indonesian Hospital, who asked not to be named.

Palestinian health officials said 18 people had been killed in Jabalia and eight elsewhere in Gaza in Israeli strikes.

The Israeli military said troops were continuing ground operations across the Gaza Strip. It said in a statement that over the past day, troops had dismantled Hamas infrastructure and tunnel shafts and killed its members in the Jabalia area. It did not comment on the immediate situation regarding the hospitals and camps.

Israel has intensified its campaigns both in Gaza and Lebanon days after the killing of Hamas leader Yahya Sinwar raised hopes of an opening for ceasefire talks to end more than a year of conflict.

Israel has vowed to eradicate the Hamas group who formerly controlled Gaza, but in doing so has laid waste to much of the territory and killed over 42,600 people. More than 1.9 million people have been left homeless amid a humanitarian crisis.

Running out

Hadeel Obeid, a supervisor nurse at the Indonesian hospital, where 32 patients are currently being treated, said they were running out of medical supplies.

"Sterile gauze is going to finish and there are no medications to give them," she told Reuters via a chat app.

Obeid said the water supply has been cut off and there was no food for the fourth consecutive day. She appealed to international organizations to take action to save the wounded.

The United Nations said it had been unable to reach the three hospitals in northern Gaza. It demands access to allow aid into northern Gaza areas.

The U.N. Human Rights Office said it was "increasingly concerned that the manner in which the Israeli military is conducting hostilities in North Gaza, along with unlawful interference with humanitarian assistance and orders that are leading to forced displacement, may be causing the destruction of the Palestinian population in Gaza's northernmost governate through death and displacement."

Israel says it is getting large quantities of humanitarian supplies into Gaza with land deliveries and airdrops. It also says it has facilitated the evacuation of patients from the Kamal Adwan Hospital.

Palestinians say no aid entered northern Gaza areas where the operation is active.

Residents and medics said Israeli forces had tightened their siege on Jabalia, the largest of the enclave's eight historic refugee camps, which it encircled by sending tanks to the nearby towns of Beit Hanoun and Beit Lahiya and issuing evacuation orders to residents.

"We are facing death by bombs, by thirst and hunger," said Raed, a resident of Jabalia camp. "Jabalia is being wiped out and there is no witness to the crime, the world is blinding its eyes,"

Israeli officials claim evacuation orders were aimed at separating Hamas fighters from civilians and denied there was any systematic plan to clear civilians out of Jabalia or other northern areas. It said forces operating in northern Gaza killed scores of Hamas members and dismantled infrastructure.

Hamas accused Israel of carrying out acts of "genocide and ethnic cleansing" against the people of northern Gaza to force them to leave.

Elsewhere in the enclave, Israeli strikes killed at least five people in Rafah in the southern Gaza Strip and four in two separate strikes in Gaza City, medics said.