Hostilities between Israel and Hamas escalated overnight, with at least 35 killed in Gaza and five 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, as the Islamist group and other Palestinian militants fired multiple rocket barrages at Tel Aviv and Beersheba, reports Reuters.
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.
It was the heaviest offensive between Israel and Hamas since a 2014 war in Gaza, and prompted international concern that the situation could spiral out of control.
UN Middle East peace envoy Tor Wennesland tweeted: "Stop the fire immediately. We're escalating towards a full scale war. Leaders on all sides have to take the responsibility of de-escalation.
"The cost of war in Gaza is devastating & is being paid by ordinary people. UN is working w/ all sides to restore calm. Stop the violence now," he wrote.
Into the early hours of Wednesday morning, Gazans reported their homes shaking and the sky lighting up with Israeli attacks, outgoing rockets and Israeli air defence missiles intercepting them.