DEIR AL-BALAH, Gaza Strip (AP) An Israeli strike early Thursday on a school sheltering displaced Palestinians in central Gaza killed at least 33 people, including 12 women and children, according to local health officials. The Israeli military said that Hamas militants were operating from within the school.

It was the latest instance of mass casualties among Palestinians trying to find refuge as Israel expands its offensive. A day earlier, the military announced a new ground and air assault in central Gaza, pursuing Hamas militants it says have regrouped there.

Troops repeatedly have swept back into parts of the Gaza Strip they have previously invaded, underscoring the resilience of the militant group despite Israels nearly eight-month onslaught .

Witnesses and hospital officials said the predawn strike hit the al-Sardi School, run by the United Nations agency for Palestinian refugees known by the acronym UNRWA. The school was filled with Palestinians who had fled Israeli operations and bombardment in northern Gaza, they said.

The hospital initially reported that nine women and 14 children were among those killed in the strike on the school. The hospital morgue later amended those records to show that the dead included three women, nine children and 21 men. It was not immediately clear what caused the discrepancy. An Associated Press reporter had counted the bodies but was unable to look beneath the shrouds.