Israeli tank fire has reportedly killed at least 40 Palestinians and injured many more at a UN-run school in Gaza. Two tank shells exploded near to the school, spraying shrapnel in and outside the building. Palestinian medical officials say many people in the school in the north of Gaza were seeking refuge from fighting between Israeli soldiers and Hamas militants.While the number of casualties has yet to be confirmed it was the second Israeli assault on a UN school today. Three people are reported to have died in that earlier attack after an air strike. The Israeli army says it is looking into the reports.