In a press conference in the Defense Ministry in Tel Aviv on Tuesday, Defense Minister Amir Peretz told reporters that, following an intensive three-day investigation, the IDF "has enough findings to demonstrate that [the Friday death of seven Palestinian civilians in an explosion on the Gaza beach] was not of our doing." The evidence was being presented first and foremost to the Israeli people, Peretz emphasized. "We owe it to ourselves to know that we did not cause these deaths." Peretz also expressed "regret that today, during an event in which our forces acted against an attempt to launch a Grad missile into Israel, innocent Palestinian citizens were also killed." Even so, he said, "All the organizations acting against us are trying to hurt our civilians. They act from within population centers through the conscious knowledge that they are endangering the population." Peretz called on Palestinians "not to allow them to act from inside population centers." Echoing Peretz's words, IDF Chief of Staff Lt.-Gen. Dan Halutz said that the events had to be understood in the context of the ongoing struggle against Palestinian Kassam attacks on the western Negev. "In the last weeks, residents of the western Negev have sustained barrages of Kassam rockets, and we are acting to reduce this phenomenon," Halutz said. "These groups fire from inside populated areas. The price the Palestinians are paying lies on the shoulders of the Palestinian [organizations]." "The sorrow we expressed [for Friday's deaths] remains, but the responsibility for that incident is not ours. Even though it is difficult to convince those who will not believe, I believe what we are demonstrating now." At the press conference, Deputy Head of the IDF Ground Forces Command Maj.-Gen. Meir Kalifi, who was in charge of investigating the incident, presented evidence that IDF fire could not have caused the explosion that killed seven Palestinian civilians on Friday. Among the evidence presented at the press conference, Kalifi showed aerial photographs of IDF attacks on northern Gaza showing that navy shells could not have caused the explosion. "We can account for every 76-mm shell fired from the navy boats. All were successful hits." In fact, Kalifi said, "the ones that fell closest to the location of the incident were fired four hours earlier." Artillery shelling could also not have been responsible for the explosion, Kalifi told reporters. While giving medical care to one of the victims in an Israeli hospital, IDF medics extracted a piece of shrapnel that, according to Kalifi, simply could not have come from the artillery forces' 155-mm guns.