Talkback quota is full. To respond to this article click here. Talkbacks 1-200 In the deadliest attack since Israel started its offensive against Hizbullah 19 days ago, 57 civilians - most of them children - were killed on Sunday in a building in the southern Lebanese village of Kafr Kana, apparently as a result of an IAF missile strike. While the entire Israeli political echelon expressed regret for the results of the strike, Air Force Chief of Staff Brig.-Gen. Amir Eshel said Sunday night that the three-story building had been struck by the missiles a little after midnight and that it only collapsed seven hours later, at close to 7 a.m. Eshel refrained from specifying what had caused the structure to collapse seven hours after it was hit, but senior IAF officers said Sunday night that the explosion could have been caused by an unexploded missile or by a Hizbullah-planted explosive device. "It could be that there was something in the building that caused the explosion," Eshel said. Eshel said that close to 150 Katyusha rockets had been fired from the Lebanese village over the past 20 days. Hizbullah had hidden rocket launchers, Eshel said, in civilian buildings in the village. Video footage he presented at a press conference in Tel Aviv Sunday night showed rocket launchers being driven into the village following attacks on northern Israel. The dead were old people, women and children from four families whom residents said had gathered to spend the night on the ground floor, where they felt they were safe from Israeli attacks. The bodies of at least 27 children were found in the rubble, said Abu Shadi Jradi, a civil defense official at the scene. In 1996, Israel was forced to suspend Operation Grapes of Wrath against Hizbullah after IDF artillery shells killed more than 100 civilians seeking refuge in a UN building in the village. A high-ranking IAF officer said the IDF had warned Kafr Kana residents to evacuate the village in anticipation of airstrikes on Katyusha launchers. The officer said the air force had been targeting the village for the past three days and that on Saturday night it struck 10 targets there. He said the building hit Sunday was chosen as a target after intelligence indicated that Hizbullah guerrillas were hiding inside, where Katyusha rockets and launchers were also hidden. "We warned the residents that we would be attacking there," the high-ranking officer said. "We work under the assumption that the villages are empty and that whoever is there is affiliated with Hizbullah." The IAF did attack targets in the village at 7 a.m. Sunday, Eshel said, but these buildings were 500 meters away from the building where the civilians were killed. Prime Minister Ehud Olmert expressed deep regret for the harm inflicted on the civilians in Kafr Kana. "I, along with Israel and the IDF, express deep regret at the death of civilians in Kafr Kana," said Olmert. "There is nothing further from our intent than when we hit civilians - everyone understands that. When we do harm civilians, the whole world recognizes that it is an exceptional case that does not characterize us." Olmert said the area was a focal point for the firing of Katyusha rockets at Kiryat Shmona and Afula. He said that from the outset of the current violence, "hundreds of rockets have been fired from the Kana area." Defense Minister Amir Peretz also profoundly regretted the fatal strike, saying, "This is a tragic incident that is the result of a war against Hizbullah, which is operating from civilian areas and knows full well that by so doing it is endangering lives." The defense minister ordered the IDF to conduct a thorough investigation into the incident. IDF Chief of General Staff Lt.-Gen. Dan Halutz also expressed sorrow over the loss of innocent life. "We were operating in a place from where Katyushas are being fired and we distributed notices to residents. Unfortunately, people who assembled in the area, whom we were unaware of, were harmed," said Halutz. Nevertheless, Halutz said, the IDF would continue to fight to protect northern Israel and to bring calm to the region. "The terrorist organizations are taking cover among populated areas," he said. "We will continue to fight, causing the minimum harm to civilians." Lebanese Prime Minister Fuad Saniora demanded an immediate and unconditional cease-fire and an investigation into the attack. US Secretary of State Condoleezza Rice said she had called Saniora to say she would be postponing a visit to Beirut scheduled for Sunday and that she had work to do in Jerusalem to end the fighting. "We are also pushing for an urgent end to the current hostilities, but the views of the parties on how to achieve this are different," she said. AP contributed to the report.