A family, including six children, have been killed in the central Gaza Strip, in the latest waves of Israel’s deadly attacks across the besieged Palestinian territory.

At least 23 Palestinians were killed overnight and into Sunday, according to numbers from local health authorities.

The parents and their six children were killed in Deir el-Balah in the central part of the Strip, Al-Aqsa Martyrs Hospital said. The grandfather of the children said their mother worked for the United Nations.

“My daughter, together with her husband and six children, was sleeping peacefully at home in Dier al-Balah. They were taken by surprise, an Israeli missile landed over their heads. The entire house was flattened. They were all killed,” Mohammed Awad Khattab told media.

“My daughter has been struggling to have children for years. She had those children through IVF … What wrong did those innocent children do? Were they posing any danger to Israel? Were they carrying arms?” he asked.

Israel’s 10-month-long offensive has so far killed more than 40,000 Palestinians in Gaza.

Elsewhere in the strip on Sunday, an Israeli aircraft bombed two apartment buildings in the Jabalia refugee camp, killing at least four Palestinians, the Wafa news agency reported.

Late on Saturday, an attack near the southern city of Khan Younis killed four people from the same family, including two women, according to Nasser Hospital.

According to UNWRA, the UN agency for Palestinian refugees, areas designated as so-called “humanitarian zones” in Gaza by the Israeli military have shrunk to just 11 percent of the Strip, “causing chaos and fear among the displaced”.