Israel has carried out hundreds of air strikes in Gaza as the Islamist group Hamas and other Palestinian militants fired multiple rocket barrages over the border at Tel Aviv and the southern city of Beersheba.
At least 35 people have been killed in Gaza and five in Israel in the most intense exchanges for years.
In Gaza, one multi-story residential building, whose occupants were warned in advance by Israel to evacuate, collapsed and another was heavily damaged after they were repeatedly hit by Israeli air strikes.
Israel said its warplanes had targeted and killed several Hamas intelligence leaders early on Wednesday. Other strikes hit what the military said were rocket launch sites, Hamas offices and the homes of Hamas leaders.
It was the heaviest offensive between Israel and Hamas since a 2014 war in the Hamas-ruled enclave, and prompted international concern that the situation could spiral out of control.
“Israel has gone crazy,” said one man on a Gaza street, where people ran out of their homes as explosions rocked the city.
Many Israelis also spent a sleepless night, with sirens sounding at 3am in Tel Aviv, heralding several waves of rocket strikes in Israel’s heartland.
UN Middle East peace envoy Tor Wennesland said the UN was working with all sides to restore calm.
Gazans’ homes shook and the sky lit up from Israeli attacks, outgoing rockets and Israeli air defence missiles.