A blast in northern Gaza that killed a Palestinian mother and her four children last Monday was not caused by the Israel Air Force, an investigation conducted by the IDF Southern Command concluded on Friday. Col. Shai Alkilai conducted the probe over the last few days, at the instructions of OC Southern Command Maj.-Gen. Yoav Galant and OC Air Force Maj.-Gen. Elazar Shkedi. The blast in question occurred on Monday morning in the northern Gaza town of Beit Hanun, when according to Palestinians, an IDF tank shell hit the home of the Abu Meatak family, as the mother, Miyasar, was preparing breakfast for her children. She was killed together with the four children. According to the probe, four terrorists were spotted carrying weapons and explosives on their backs near the home. The IAF fire was on target and only hit the armed terrorists. Secondary explosions were ignited that destroyed the home and killed the mother and her children. The IDF investigation ruled out the possibility that the family was hit by IDF fire, and revealed that the secondary blast was far larger than the explosion that was caused by the initial IDF bombing. It was unfortunate that innocent people were killed, the IDF said, but the blame lay with Hamas for operating from populated areas and using civilians as human shields. "There was no reason that the explosion should come from us. We know that it was material they carried," said IDF spokeswoman Maj. Avital Leibovitz. "They were going out to battle in the middle of a residential neighborhood." The military released grainy video of the strike in which four figures, which the IDF said were the armed terrorists, are seen walking near a home. The video shows two strikes against the terrorist group and how during the second strike a secondary explosion blew what looks like a flare in the direction of the Abu Meatak home. B'tselem, a Palestinian-rights group, called for a wider criminal probe of the incident, saying the IDF appeared to have violated international law by firing close to the family's home. B'tselem spokeswoman Sarit Michaeli said whose weapons actually killed the family was less significant than the fact that the IAF attacked in a populated area. "They need to investigate the decision to fire a missile right next to the home," she said. AP contributed to this report.