What does Gaza hospital blast evidence show

A deadly blast at the crowded Al-Ahli hospital in Gaza City is feared to have killed hundreds of people. The Hamas-controlled Palestinian authorities in Gaza immediately blamed Israel, claiming it was a deliberate air strike. Israel has denied involvement. Amid the claim and counter-claim, getting to the truth is harder than ever. BBC Verify has analysed video footage, still imagery and other evidence, including eyewitness accounts.