An Israeli air strike in southern Gaza hours before a humanitarian truce was declared killed 20 Palestnians, including 11 children, most of them from a single family, medics said.

The strike in southern Khan Yunis hit the home of the Najjar family, killing at least 14 members of the clan, emergency services spokesman Ashraf al-Qudra said.

Another two members of the Abu Shahla family were killed, along with four other people, two of whom have yet to be identified.

The dead included 11 children, among them a one-year-old girl and a three-year-old boy, Qudra said.

The strike raised the toll in Gaza on the 19th day of assault on Gaza to at least 891 people, before a  12-hour ceasefire went into effect.

The toll is expected to rise as bodies are pulled from the rubble of homes in some of the worst-hit parts of Gaza, in northern Beit Hanun, eastern Shejaiya and Zaitun, and southern Khan Yunis.

*This story has been edited by Ahram Online.