New Delhi, Aug 01 (ANI): Secretary of State John Kerry said that ceasefire at some point is essential in Gaza and US remains hopeful that it is achievable. At dawn on Wednesday, Israeli forces shelled a girls' school doubling as a refuge for more than 3,000 people, killing at least 15, including four children. Gaza officials say more than 1,370 Palestinians, most of them civilians, have been killed in the battered enclave and nearly 7,000 wounded. Israel says 56 of its soldiers and three civilians have been killed. Kerry said he had remained in close contact on the telephone with players in the Middle East to try ending the Israel-Hamas conflict. International calls for a ceasefire have grown as the death toll has mounted in the worst flare-up of Israeli-Palestinian violence in almost two years, sparked by the murder of three Israeli teenagers and revenge killing of a Palestinian youth.