JERUSALEM (CNN) -- Israeli Defense Minister Ehud Barak told U.N. Secretary-General Ban Ki-moon on Thursday that the shelling of a U.N. relief agency's compound in Gaza City was "a grave mistake," the U.N. chief said.
Smoke drifts Thursday from the obscured United Nations compound in Gaza City.
1 of 3 "I conveyed my strong protest and outrage to the defense minister and the foreign minister and demanded a full explanation," Ban said at a news conference in Tel Aviv, Israel.
He added that Barak took the matter "very seriously."
Ban said he called Barak, before meeting with him later in the day, to ask him to explain the shelling of the U.N. Relief and Works Agency compound.
The UNRWA headquarters was hit repeatedly by shrapnel and artillery during clashes Thursday morning, UNRWA Director John Ging said. Three workers were hurt, and the compound's warehouse and workshop were burning out of control within an hour and a half, he said. Watch as fire blazes at U.N.
Israeli government spokesman Mark Regev said it was "not clear whose shells, whose fire hit the U.N. facility."
The Foreign Press Association said international news agency offices in Gaza City were hit by Israeli fire Thursday and demanded Israel stop shooting at the building that houses them.
Israeli forces have attacked a media building in Gaza City, wounding two people as Tel Aviv intensifies its military campaign in the region.
Al-Shurouq Tower, housing several media organizations, was hit by an Israeli missile on Thursday. The missile hit the 13th floor of the 16-story building. A journalist and a cameraman working for Abu Dhabi TV were injured in the attack.
"Each missile we shoot is pinpointed to the very metre we want it to go."