A Palestinian mother comforts her child, after what medics said was an Israeli shell that hit a U.N-run school sheltering Palestinian refugees, at a hospital in Jabaliya in the northern Gaza Strip on July 24, 2014. Reuters/Finbarr O'Reilly

The Israeli military acknowledged firing a mortar shell that hit the courtyard of a school in northern Gaza Thursday, but denied it was responsible for any deaths at the United Nations-run school, CNN reported Sunday.

"In light of the results of the investigation, claims that people were harmed inside school grounds, as presented after the incident by some, have been ruled out,” the army said, according to The Jerusalem Post. “The IDF regrets every harm to civilians in combat, but stresses again that this is the sad result of Hamas's decision to use the civilian sphere as a human shield.”

The school was doubling up as a shelter for Gaza residents seeking refuge from the violence, but the Israeli military said it did not kill anyone claiming video footage showed there was no one in the courtyard at the time the missiles were fired. However, according to U.N. officials and the Palestinian government, 16 were killed and hundreds were wounded by the strike.

"A single errant Israeli mortar landed in the courtyard in the school," Israel Defense Forces spokesman Lt. Col. Peter Lerner said, according to CNN. "The footage we have shows the courtyard was empty."

Fighting was reportedly intense between IDF and Hamas on Thursday, and militants reportedly fired missiles from near the school and IDF fired back in that direction.

"We reject the claim that people were killed by the IDF mortar on the school premises," Lerner said.

The U.N. Relief and Workers Agency, or UNRWA, said there would be a full investigation of the school bombing, but didn’t reveal who would lead the probe.

"It is important in a case like this where a UN school in which hundreds of people took refuge is hit in this way, that there should be full transparency and accountability," Chris Gunness, a spokesman for the UNRWA, said Sunday, as quoted by Ynet.news.com.

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