Forty killed after Israeli shell hits UN-run school in GazaAt least 40 Palestinians were killed when an Israeli tank opened fire outside a UN-run school in the Gaza, the second attack on a school in the war torn enclave in just one day.Two tank shells exploded outside the school, spraying shrapnel on those inside and outside the building, where hundreds of Palestinians had sought refuge from fighting between Israeli soldiers and Hamas militants. Bodies lay scattered on the ground in pools of blood amid shredded clothes and shoes after the attack, in which several dozen people were also wounded. Israel has continued to defy international calls for a ceasefire as they moved their troops deeper into southern Gaza to intensify their ground offensive. Those who died in the attack today were both those sheltering in the school and local residents, medical officials at two local hospitals said. Schools run by the UN Palestinian refugee agency have opened their doors to provide shelters from Israeli attacks. At least 17 are running as shelters for more than 5,000 people. Nine of the schools in the Jabaliya refugee camp – are in the front line of fighting. Earlier today three people were killed at another UN-run school when Israeli tank fire showered the building where they were sheltering from the conflict. More than 600 people have lost their lives during the battle between Israeli forces and Hamas militants which is now in its 11th day. A quarter of those are civilians according to the UN. A further night of fierce and increasingly chaotic battle which saw Israel intensify its ground offensive. Four Israeli soldiers were killed and 30 wounded in two separate “friendly fire” incidents, three of them were killed when the building they were occupying was hit by one of their own tanks. The fourth soldier, whose death has just been announced, was killed by an errant tank shell. Five Israeli soldiers have now died since the start of ground incursions into Gaza on Saturday.