A United Nations Relief and Works Agency spokesman charged Wednesday that the Israeli military has privately admitted that militant gunfire did not emanate from a school in the Northern Gaza Strip that was shelled by the IDF on Tuesday and called for an independent investigation. "The Israeli army in private briefings with diplomats have admitted that the militant fire from Jabalya yesterday came from outside the UNRWA school compound and not inside the UNRWA school compound," said Christopher Gunness, a spokesman for the UN Relief and Works Agency. "This was a very serious allegation against a United nations human development agency, which a day later turned out to be totally wrong, which is why we wonder what other information might be wrong and why we are calling for an impartial investigation." He declined to say to which diplomats the statement was made. The shelling killed 40 people who had taken shelter from Israel's military operation and wounded dozens more, Gunness said. But IDF officials maintained Wednesday that a number of mortar shells were fired at IDF units "from within the Jabalya school. In response to the incoming enemy fire, the forces returned mortar fire to the source." An IDF statement said that two Hamas operatives, Imad Abu Ashkar and Hassan Abu Ashkar, were among the bodies found at the school. A spokeswoman declined to explain, however, how the operatives were identified. She said that the IDF did not have any video of this particular incident. Earlier in the day, Gunness said that they are "99.9 percent certain that there were no militants or militant activity in the school or in the school compound" following a preliminary investigation conducted by the relief and human development agency. "We've spoken to eyewitnesses, we've spoken to some of the 1,300 [people who] took refuge there, we have a very experienced investigator who went up there, he talked to everyone we can get a hold of," he said. Two residents of the area reached by phone told the Associated Press that they saw a small group of gunmen firing mortar rounds from a street near the school, where 350 people had gathered to get away from the shelling. They spoke on condition of anonymity for fear of reprisal. In addition, Palestinian residents said that several gunmen ran toward the crowd, trying to use it as cover, when the first Israeli mortar shell missed them. Meanwhile, strong condemnations were renewed throughout the Arab world and mass protests took place in countries like Sudan, Lebanon and Jordan as photos of dead children were broadcast by satellite television stations. Much of the Arab press condemned Israel for the Jabalya incident, with some comparing it to the incident in the Lebanese village of Qana in 1996, in which the IDF fired an artillery shell that hit a UN outpost in the village that was serving as a shelter for residents, killing more than 100 Lebanese civilians. The Kuwaiti newspaper al-Qabas called Tuesday's incident near Jabalya "one of the worst massacres against defenseless Palestinian civilians" committed by "the Israeli war machine." "This massacre reminds us of a similar bloody massacre committed by Israel in Lebanon during the Operation Grapes of Wrath in April 1996, when the UN headquarters, which sheltered people in the village of Qana, was targeted and 105 people, mostly women and children, were killed," it added. The Syrian News Agency Sanna said Wednesday that "Israeli aggression does not differentiate between humans and stones" in its attacks. These initial reports about the incident did not include the Israeli claim that gunmen had fired from the school. Lebanese Prime Minister Fuad Siniora was quoted in the Lebanese newspaper el-Mustaqbal as saying: "The Israeli targeting and killing of innocent women and children civilians is described as a war crime in front of the eyes of the world" but without serving as a "deterrent" for Israel. He added: "This massacreâ€¦takes us back to the painful memories of the massacres committed by Israel more than once in Lebanon. and specifically in the village of Qana and other Lebanese villages." But at least some Israeli analysts say they don't think the attack will have an impact on Israel's operation. The incident "happened towards the end of the operation. Everyone is finalizing a cease-fire," said Eyal Zisser, director of Tel Aviv University's Moshe Dayan Center for Middle Eastern Studies. "I think those who supported it before are OK with it. Those who didn't support it are still opposing Israel." AP contributed to this report.