Hostilities between Israel and Hamas escalated overnight, with at least 48 Palestine Muslims killed in Gaza and five people killed in Israel in the most intensive aerial exchanges for years.
Israel carried out hundreds of air strikes in Gaza into the early hours of Wednesday.
One multi-story residential building in Gaza collapsed and another was heavily damaged after they were repeatedly hit by Israeli air strikes.
Israel said its jets had targeted and killed several Hamas intelligence leaders early on Wednesday. Other strikes targeted what the military said were rocket launch sites and Hamas offices.