According to another report, broadcast by Al-Jazeera television, Israeli tank shells hit the front gate of the school. UNRWA Spokesperson Christopher Gunness confirmed that at least one shell landed near the school.

Children are also said to be among the dead. Hundreds of people were reported to be in the area of the school at the time of the shelling.

Ma’an’s reporter said that dozens more, all civilians, were injured in the attack on the Al-Fakhoura School. The death toll is expected to rise as a number of the wounded are said to be in critical condition. Ambulances were initially unable reach the school.

The school is operated by UNRWA, the UN's agency for Palestinian refugees. UNRWA has been using its schools to house some of the 15,000 Gazans who have fled their homes due to Israel's ground invasion of the Gaza Strip, which began on Saturday.

UNRWA says it handed over the GPS coordinates of all UN installations throughout the Gaza Strip to the Israeli military. The school was clearly marked as a UN facility.

Earlier on Tuesday, the United Nations confirmed that three refugees had been killed at 11:30 on Monday night when Israeli forces fired directly on a UNRWA school in Gaza City. Another UNRWA school also came under fire in the city of Rafah.

"There's nowhere safe in Gaza. Everyone here is terrorized and traumatized," said John Ging, the top UN official in Gaza. He also said that people in Gaza are "entitled" to action by the international community to stop the Israeli invasion.

"I am appealing to political leaders here and in the region and the world to get their act together and stop this," he said, speaking at Gaza's largest hospital. "They are responsible for these deaths."

Tuesday's attack has drawn comparisons to the 1996 Israeli shelling of a UN compound in Qana, southern Lebanon, in which 106 civilians were killed.