Israeli bombing of a school hosting displaced people in the Al-Nuseirat refugee camp in central Gaza has killed 40 people, including 14 children and nine women, two Gaza officials said on Thursday.
An Israeli air raid overnight targeted the Al-Sardi school, which was crowded with displaced people who had fled eight months of ferocious and indiscriminate Israeli war on the Gaza Strip.
Among the injured and killed were children whose bodies arrived in pieces at the Al-Aqsa Martyrs Hospital in the city of Deir Al-Balah.
The Gaza government media office condemned the attack as a "horrific massacre… that shames humanity".
"We hold the Israeli occupation and the American administration fully responsible for the crimes against humanity being committed in Gaza," the media office said.
The Israeli army claimed it had targeted a "Hamas compound" inside the school, which belongs to the United Nations agency for Palestinian refugees UNRWA.
"Fighter jets… carried out a precise strike targeting a Hamas compound inside a UNRWA school in the Al-Nuseirat area," the army said in a statement.
The director of the Gaza government media office, Ismail Al-Thawabta, and a Gaza health ministry official told Reuters that 40 people were killed and 73 were wounded.
The two officials added that 14 children and nine women were killed in the strike.
Earlier, UNRWA communications director Juliette Touma told Reuters that the number of those reported killed in the Israeli offensive on the Nuseirat school was between 35 and 45, adding that the number could not be confirmed at this stage.
An Israeli military spokesperson claimed the army assessed that there were 20 to 30 fighters located in the school.
Lieutenant Colonel Peter Lerner said many of the fighters had been killed and said he was unaware of civilian casualties from the strike.
A medic at the facility said another Israeli pre-dawn strike killed six people in a house in the Al-Nuseirat refugee camp, while witnesses reported intense artillery shelling in Bureij and Al-Maghazi camps in the same area.
Israeli warplanes also carried out strikes in eastern and central neighbourhoods of Rafah, Gaza's southernmost city, a local source told AFP.
Israeli forces intensified raids and artillery shelling in central Gaza in recent days, also carrying out a ground incursion focused on the Al-Bureij refugee camp and Deir Al-Balah.
The administration of Al-Aqsa Martyrs Hospital in Deir al-Balah announced on Wednesday that one of its two power generators had broken down.
This threatens to create a "humanitarian disaster" that could lead to the deaths of dozens of wounded people, patients, and premature babies, amid the Israeli incursion.
Israel's war on Gaza has so far killed at least 36,586 people, according to the Palestinian territory's health ministry.
The brutal military campaign has seen hospitals, ambulances, and residential buildings attacked. It has also led to widespread hunger and mass displacement.
Some 31 percent of children under two in northern Gaza suffer from acute malnutrition, as do about 10 percent in Rafah in the south.
South Africa has accused Israel of genocide at the International Court of Justice and a number of other countries, most recently Spain, have supported it in its accusation.
Reuters and AFP contributed to this report.