The Guardian reports: At least 11 members of one family, including five women and four children, were killed when Israel bombed a house in Gaza City on Sunday as the five-day-old war claimed more civilian lives with no sign of a let-up in the intense bombardment.

The air strike flattened the home of the Dalou family in the Sheikh Radwan district of Gaza City, causing the biggest death toll in a single incident since the offensive began last Wednesday.

On Monday morning the Israeli defence force appeared to admit the family had been killed by mistake. The Haaretz website quoted the army as saying their house was either incorrectly pinpointed or a missile malfunctioned.

Elsewhere in the city early Monday an air strike levelled two houses belonging to a single family, killing two children and two adults and injuring 42 people, including children, said Gaza heath official Ashraf al-Kidra. Rescue workers were frantically searching for 12 to 15 members of the Azzam family under the rubble. Shortly afterwards, Israeli aircraft bombarded the remains of the former national security compound in Gaza City. Al-Kidra said flying shrapnel killed one child and wounded others living nearby.

After the Dalou family home was destroyed, the bodies of the children were pulled from the rubble and taken to the morgue at Shifa hospital. The dead also included an 80-year-old woman.

Ismael Haniyeh, the Hamas prime minister, described the deaths as an “ugly massacre” and the Hamas military wing, al-Qassam Brigades, said: “The massacre of the Dalou family will not pass without punishment.”

Diggers at the scene of the explosion were scooping rubble from flattened buildings as rescuers tried to locate survivors.

Witnesses said there were chaotic scenes as the dead and injured were brought to the Shifa hospital, which has been on emergency footing since the start of Operation Pillar of Defence.

The bodies of four young children lay on two metal trays in the morgue, covered in dust and blood. A crowd of onlookers outside became increasingly distressed as the body of the children’s mother was wheeled in, covered in blankets.

The strike was originally thought to have been aimed at a Hamas official, Mohamed Dalou.

In all, 84 Palestinians, about half of them civilians, have been killed in the five-day onslaught and 720 have been wounded. Three Israeli civilians have died from Palestinian rocket fire and dozens have been wounded.