Rescuers said at least 20 people were killed, mostly children, and more than 60 wounded in an Israeli strike on a school sheltering displaced people in Gaza City on Monday.

"At least 20 martyrs were transported (to hospital), the majority of them children, and more than 60 wounded in the horrific occupation (Israeli) massacre at the Fahmi Al-Jarjawi School, which was sheltering hundreds of displaced people in the Al-Daraj neighbourhood of Gaza City," civil defence spokesman Mahmud Bassal told AFP, raising the agency's previous toll from 13 dead.