"So far, 21 people have been killed as a result of an Israeli air strike on Dar al-Arqam School in the Al-Tuffah neighbourhood, northeast of Gaza City," Mahmud Bassal, the agency's spokesman, told AFP.

The Israeli military when contacted did not provide an immediate response, but said in a statement that it had struck a "Hamas command and control centre in the area of Gaza City".

"The command and control centre had been used by the terrorists to plan and execute attacks against Israeli civilians and IDF troops," the military said.

It was unclear whether it was the same attack that targeted the school.