A high-ranking IDF official will investigate the circumstances of the deaths of a Palestinian mother and her four children in Gaza on Monday, the army announced late in the day, citing the "sensitivity of the matter and the complexity of the battle" in which the five were killed. The purpose of the inquiry was to "eliminate any possible doubt" regarding the incident. The as-yet unnamed investigating officer, at the rank of colonel, was expected to submit the results of the probe to OC Southern Command Maj.-Gen. Yoav Galant and IAF chief Maj.-Gen Eliezer Shkedy within 48 hours. Earlier, the army said a probe into the incident showed that the civilians were killed by secondary explosions after the IAF bombed a pair of Palestinian terrorists carrying large quantities of explosives near the family's home. The blast occurred early Monday morning when, according to Palestinians, an IDF tank shell hit the Abu Meatak home in the northern Gaza town of Beit Hanun as the mother, Miyasar Abu Meatak, was preparing breakfast for her children. She was killed along with daughters Rudina and Hana, ages six and three, and sons Saleh, four, and Mousab, 15 months. A 17-year-old Palestinian bystander was also killed. "What a black day - they killed my family," wailed the grief-stricken father, Ahmad Abu Meatak, outside the hospital where the bodies were taken. Abu Meatak said he had been on his way to a nearby market to shop when the tank shell hit. The force of the blast scattered clothes and other household items outside the two-room home. A single white children's shoe, flattened by the explosion, lay on the ground near a blue pair of shorts covered in sand. A green baby seat, one end bent, stood empty. According to the IDF, the explosion occurred after an Israeli aircraft fired a missile at two Palestinian terrorists who were spotted next to the family home. The terrorists, the IDF said, were carrying explosive devices, which subsequently detonated, causing a secondary explosion that destroyed the home and killed Miyasar and her four children. The IDF did not provide evidence to back up its claim, but said that a thorough probe had been conducted by OC Gaza Division Brig.-Gen. Moshe Tamir. "We see Hamas as responsible for everything that happens there, for all injuries," Defense Minister Ehud Barak said. "Hamas is also responsible, by operating within the civilian population, for some of the civilian casualties." IDF operations continued throughout the day in Gaza, as close to 20 Kassam rockets were fired into Israel - one of which scored a direct hit on a home in Sderot. No one was wounded in the attacks. One soldier was lightly wounded during the Gaza operations. Palestinian Authority President Mahmoud Abbas condemned the shelling, saying it would make peace negotiations with Israel even more difficult. "We emphasize the need to achieve calm and keep our people away from the agony of war and destruction," he said. Also responding to the strike, Hamas Prime Minister Ismail Haniyeh accused Israel of striving "to ruin any regional and international efforts to end the siege and halt aggression." A Hamas-allied terror group, meanwhile, vowed revenge. "The blood of the children will not be spilled in vain," said Abu Mujahed of the Popular Resistance Committees. AP contributed to the report.