Rescuers said devastating Israeli strikes in the Gaza Strip killed at least 52 people on Monday, 33 of them in a school turned shelter, AFP reports.

The civil defence agency said many of the casualties at the school in Gaza City were children, while the Israeli military said the site was housing “key terrorists”.

World leaders meeting in Spain called for an end to the “inhumane” and “senseless” conflict, while aid groups said the trickle of aid is not nearly enough to staunch the hunger and health crises.

In Gaza City, civil defence agency spokesman Mahmud Bassal said that an early-morning Israeli strike on the Fahmi Al-Jarjawi school, where displaced people were sheltering, killed “at least 33, with dozens of injured, mostly children, including several women”.

The Israeli military said it had “struck key terrorists who were operating within a Hamas and Islamic Jihad command and control center embedded in an area that previously served as the ‘Faami Aljerjawi’ School”, adding that “numerous steps were taken to mitigate the risk of harming civilians”.