GAZA CITY – The Palestinian civilian death toll mounted Monday as Israeli aircraft struck densely populated areas in the Gaza Strip in a campaign to quell militant rocket fire menacing nearly half of Israel's population. An overnight air strike on two houses belonging to an extended clan in Gaza City killed two children and two adults, and injured 42 people, said Gaza heath official Ashraf Al-Kidra. Shortly after, Israeli aircraft bombarded the remains of the former national security compound in Gaza City. Flying shrapnel killed one child and wounded others living nearby, Al-Kidra said. Five farmers were killed in two separate strikes, Al-Kidra said, including three who had been identified earlier by Hamas security officials as Islamic Jihad fighters. Civilian casualties began to shoot up Sunday, after Israel said it was stepping up attacks on the homes of suspected Hamas activists. After that warning, an Israeli missile flatted a two-story house in a residential area of Gaza City, killing at least 11 civilians, most of them women and children. It remained unclear who the target of that missile attack was. However, the new tactic ushered in a new and risky phase of the operation, given the likelihood of civilian casualties in the crowded territory of 1.6 million Palestinians. The rising civilian toll was also likely to intensify pressure on Israel to end the fighting. Hundreds of civilian casualties in an Israeli offensive in Gaza four years ago led to fierce international condemnation of Israel. In all, 87 Palestinians, including 50 civilians, have been killed in the six-day onslaught and 720 have been wounded. Three Israeli civilians have died from Palestinian rocket fire and dozens have been wounded. An Israeli rocket-defense system has intercepted hundreds of rockets bound for populated areas. Monday's air assault in Gaza City reduced two houses to rubble on either side of a street where residents stepped over piles of cinderblocks and twisted metal. Relatives said Ahed Kitati, 38, had rushed out after a warning missile was fired to try to hustle people to safety. But he was fatally struck by a falling cinderblock, leaving behind a pregnant wife, five young daughters and a son, they said. One of his daughters, Aya Kitati, clutched a black jacket, saying she was freezing, even though the weather was mild. “We were sleeping, and then we heard the sound of the bombs,” she said in a whisper, then broke down sobbing. Ahed's brother, Jawad Kitati, said he plucked the lifeless body of a 2-year-old relative from the street and carried him to an ambulance. Blood stains smeared his jacket sleeve. Another clan member, Haitham Abu Zour, 24, woke up to the sound of the warning strike and hid in a stairwell. He emerged to find his wife dead and his two infant children buried under the debris, but safe. – AP