The Hamas state media office announced that 15 children and 8 women were among those killed in the attack in the center of Deir al-Balah. The Media Office and the Gaza Ministry of Health announced that more than 100 people were injured.
The Israeli military said it had targeted fighters operating there and had taken measures to reduce the risk to civilians.
Separately, nine people were killed in an Israeli rocket attack on a soccer field in the occupied Golan Heights on Saturday.
In Al-Aqsa Hospital in Deir al-Balah, ambulances quickly brought the injured to the place for treatment. Some people came on foot, and their clothes were bloody.
Reuters images show people returning to the site of the bombing to check their belongings, and fires erupting in the area.
Umm Hasan Ali, a displaced woman living in the school, said it had only been a few months since she returned to Gaza from Egypt with her daughter, who was taken there for treatment.
The army announced on Saturday that it had ordered Palestinians to evacuate the southern neighborhoods of Khan Yunis and move to the al-Mawasi humanitarian zone. Health authorities announced that the Israeli attacks in Khan Yunis on Saturday left 14 dead.
The United Nations and humanitarian officials accuse Israel of using disproportionate force in the war and failing to ensure safe havens for civilians, which it denies.
In the occupied West Bank by Israel, Nabil Abu Rudineh, the spokesman of Palestinian President Mahmoud Abbas, accused the Israeli attacks of US support.
According to Latest News, a rocket fired from Lebanon hit a soccer field in an Arab town in the Golan Heights on Saturday, killing 11 youths, in what the military described as "the deadliest attack on Israeli civilians since October 7."
The Israeli military claimed that Lebanon's Hezbollah group fired a deadly rocket that killed youths aged 10 to 20 when it hit the ground in the city of Majdal Shams.
Hezbollah denied responsibility for the deadly attack. Referring to its military branch, the Islamic Resistance said: The Islamic Resistance has nothing to do with this incident.
Israeli army spokesman Daniel Hagari said on X-Day that 11 youths were killed in the attack, while the Magen David Edom emergency service said 19 others were wounded when a rocket hit Majdal Shams.
