Israel’s prime minister has warned people living in Gaza to leave as he vowed to turn parts of the territory “into rubble” in revenge for a “black day”.
Benjamin Netanyahu earlier said Israel was at war with Palestinian militants from Hamas, which governs Gaza, after their fighters launched a surprise attack on Saturday morning.
Rescue service officials told Israeli media at least 250 people were killed in the deadliest attack on the country in decades.
Netanyahu says war will ‘take time’ – follow live updates
Israel’s health ministry said at least 1,590 people had been injured.
Meanwhile, the Palestinian health ministry said at least 232 people had died and 1,700 wounded in Israel’s retaliatory airstrikes on Gaza.
In a televised address, Mr Netanyahu said the country’s military would “take revenge for this black day”, but warned: “This war will take time. It will be difficult.”
In a statement on X, he wrote: “All of the places which Hamas is deployed, hiding and operating in, that wicked city, we will turn them into rubble.
“I say to the residents of Gaza: Leave now because we will operate forcefully everywhere.”
Rockets were seen landing on Gaza hours after Mr Netanyahu issued the threat.
Israel will also stop supplying electricity, fuel and goods to Gaza, which is already blockaded, according to a statement from Mr Netanyahu’s office.
Much of Gaza was already thrown into darkness by nightfall after electricity from Israel, which powers almost all of the territories, was cut off earlier in the day.
Mr Netanyahu said the “first phase” of the counteroffensive had ended and that Israel had fought off the majority of Hamas militants.
He vowed to continue “without reservation and without respite”.
‘Record year for Palestinians deaths’
Hamas gunmen targeted up to 22 locations in the initial assault, with gun battles continuing well after nightfall.
Militants held hostages in two towns and occupied a police station in a third.
Hamas’ military wing claimed it was holding dozens of Israeli soldiers captive in “safe places” and tunnels in Gaza.
The Israeli military confirmed that a number of Israelis were abducted but would not give a figure.
Palestinian activist Nour Odeh, a former Palestinian Authority spokesperson, told Sky News’ US partner NBC News that the attack comes after a record year for the number of Palestinians killed by Israel.
He said Saturday’s incursion was not the “beginning of the story” and that Israeli forces have occupied Palestinian territories for over 50 years.
Mr Odeh said: “It’s a record-setting year for the number of Palestinians killed, the number of Palestinian children killed, the number of homes demolished, the number of attacks by armed settlers that, you know, burned down homes and attack people and wounded and killed Palestinian civilians.”
Read more:
An astonishing unravelling of a situation long forgotten
Unpredented attack causes crisis – and days of war are ahead
Deeply divided Israel caught out by incursion
Sunak says Israel has right to defend itself
Israel airstrikes intensify
After nightfall, Israeli airstrikes in Gaza intensified, flattening several residential buildings in giant explosions, including a 14-storey tower that held dozens of apartments as well as Hamas offices in central Gaza City.
Israeli forces fired a warning just before and there were no reports of casualties.
Soon after, a Hamas rocket barrage into central Israel hit four cities, including Tel Aviv and a nearby suburb, where two people were seriously injured.
Throughout the day, Hamas fired more than 3,500 rockets, the Israeli military said.
In the southern Gaza city of Rafah, an Israeli airstrike late on Saturday flattened a home, killing 12 members of the Abu Qouto family, neighbours said.
Ten members of a family in the northern town of Jebalya were killed in another strike, relatives said.
It was not known why the homes were targeted.
Palestinians demonstrated in towns and cities around the West Bank on Saturday night. Palestinian health officials said Israeli fire killed five there, but gave few details.
President Joe Biden said he had spoken with Mr Netanyahu to say the US “stands with the people of Israel in the face of these terrorist assaults”.
He said: “Israel has the right to defend itself and its people, full stop.”