A dozen Palestinians were killed by Israeli attacks overnight on Saturday in the occupied Gaza Strip, emergency services said.
A total of 920 people have been injured since Israel began its campaign on Tuesday.
Gaza medical sources told Al Jazeera that three handicapped children and a medical carer were killed in the bombing of the NGO, Mercy Givers for Handicaps, in Jebaliya.
The AFP news agency also reported two dead at a charitable association for the disabled in Beit Lahiya, three deaths in the eastern Tufah area of Gaza City, and three others killed in western Gaza City.
The UN's top human rights official on Friday said the air campaign may violate international laws prohibiting the targeting of civilians.
"We have received deeply disturbing reports that many of the civilian casualties, including of children, occurred as a result of strikes on homes," said Navi Pillay, the UN high commissioner for human rights.
"Such reports raise serious doubt about whether the Israeli strikes have been in accordance with international humanitarian law and international human rights law," she said.