Updated 1:22 pm ET
An Israeli airstrike on a busy market in Gaza has killed at least 15 and wounded 150 others, the Associated Press reports.
The strike occurred during a four-hour humanitarian cease-fire,which occurred between 3pm and 7pm local time, in the Gaza Strip. The market is situated within Shejaiya , an area which Israel said wasn't protected by the parameters of its cease-fire.
A Gaza healthy ministry official, Ashraf al-Kidra, told the AP the Gazans shopping in the market believed they were protected.
In a statement released before the cease-fire, the Israel Defense Forces (IDF) said that the humanitarian window would "not apply to the areas in which IDF soldiers are currently operating" — among which is Shejaiya.
The IDF told residents not to return to areas which they were asked to evacuate, and warned "the IDF will respond to any attempt to exploit this window to harm Israeli citizens and Israeli soldiers." During the cease-fire, the AP reports, Palestinian militants did fire rockets into Israel.
The IDF scheduled the cease-fire earlier Wednesday, after another night of heavy fighting between it and Hamas saw 15 people killed in the Israeli shelling of a UN school in the Jabaliya refugee camp in Gaza.
The U.N. Relief and Works Agency said that Tuesday's attack was the sixth time the IDF had struck a U.N. school during the current conflict. In a statement on their website they called the incident "an affront to all of us, a source of universal shame. Today the world stands disgraced."
A spokesperson for the IDF told TIME: "The initial IDF investigation suggests that [Palestinian] militants fired mortar shells from the vicinity of the school," to which the IDF responded. The spokesperson added that the investigation is ongoing.
The White House condemned the UN school shelling Wednesday afternoon, the Associated Press reports, but did blame any party for it.
The shelling of the school happened during the 23rd day of operations in the Gaza strip which has so far seen over 1,258 Palestinians killed, according to Gaza's health ministry. Israel has lost 56 in the fighting.