On the sixth day of its Gaza offensive, Israel has struck its first deadly blow against the top ranks of Hamas.One of the Islamist group’s senior leaders has been killed in an air strike on his home in the Jabaliya refugee camp. A cleric, widely regarded as one of Hamas’s most hardline political leaders, Nizar Rayyan had called for renewed suicide bombings inside Israel. Several members of his family were also killed including, reportedly, his four wives and two of his daughters. Rayyan is being described as the most senior Hamas figure to be killed by Israel since 2004. Many of the group’s leaders are in hiding, anticipating assassination attempts by Israel. Hamas Radio said Rayyan rejected advice to leave his home. The head of emergency services in the Gaza Strip says more than 400 Palestinians have now been killed since the air attacks started on Saturday. A government complex was among targets Israel said it hit today. As the air strikes continue, Israel’s tanks remain on the Gaza border, poised for a possible ground invasion, as international calls for a ceasefire intensify.