Israel is calling out a United Nations aid agency for falsely claiming that the Israeli Defense Forces did not permit civilians to evacuate a Gaza school where 15 people were killed today.

The U.N. Relief and Works Agency (UNRWA) laid blame for the civilian deaths on the IDF, claiming it never received approval from the IDF for an evacuation from the facility.

UNRWA—which has been under fire in recent days for allowing Hamas to use its facilities to store rockets—released a statement claiming: "UNRWA had been attempting to negotiate with the [IDF] a pause in the fighting during which they would guarantee a safe corridor to relocate staff and any displaced persons who chose to evacuate to a more secure location. Approval for that never came to UNRWA."

Earlier, UNRWA spokesman Chris Gunness had similarly accused the IDF of preventing a civilian evacuation.

"Over the course of the day UNRWA tried 2 coodinate [sic] with the Israeli Army a window for civilians 2 leave & it was never granted," UNRWA spokesman Chris Gunness tweeted, following the strike.

However, in an unusual move late Thursday, multiple IDF sources rejected UNRWA’s claims and characterized them as outright falsehoods when reached by the Washington Free Beacon.

"For two days we were trying to move people out of that school in particular and the Beit Hanoun area in general," said an IDF official who was involved in the interactions between the IDF, UNRWA, and International Red Cross (ICRC) leading up to the incident.

The official continued: "This morning we sought a cease-fire in the area and a humanitarian evacuation of civilians, but Hamas refused—because they wanted to keep civilians in the area to protect their fighters who were firing on the IDF," the source said. The claim by Gunness and UNRWA that the IDF did not respond to their request to evacuate civilians, the source said, is "a flat-out complete and total lie."

When asked for further details about the incident, UNRWA claimed that its school in Beit Hanoun had been turned into "a battlefield" in recent days.

Many Palestinians, including women and children, had sought shelter from the fighting in the school, believing it to be safe territory, according to UNRWA.

"This is the fourth time in the past four days that an UNRWA school has been struck by explosive projectiles," UNRWA said.

An official IDF statement released to the Free Beacon states that "the IDF authorized a humanitarian time window for evacuation between 10:00-14:00 IDT earlier today. Hamas prevented the civilians from leaving it and once again used their infrastructure and international symbols as human shields. In the course of the afternoon, several rockets launched by Hamas from within the Gaza Strip landed in the Beit Hanoun area."

"From initial inquiries done about the incident, during the intense fighting in the area, militants opened fire at IDF soldiers from the school area," the statement says. "In order to eliminate the threat posed to their lives, they responded with fire toward the origins of the shooting."

"The UNRWA claims that Israel prevented the safe evacuation of the school in Beit Hanoun are unfounded," the statement concludes.

The source of the explosion is being investigated by the IDF.

"It should be emphasized that during recent days the [Coordination of Government Activities in the Territories] has been maintaining close contact with representatives of the UNRWA, the ICRC, and Palestinians in Beit Hanoun," the statement concludes. "It should be further emphasized that following this contact, the humanitarian window was authorized."