Israeli troops massed at Gaza's border on Thursday and Palestinian militants pounded Israel with rockets in intense hostilities that have caused international concern and touched off clashes between Jews and Arabs in Israel.
Days of violence between Jewish Israelis and the country's Arab minority worsened overnight, with synagogues attacked and fighting breaking out on the streets of some communities.
With concern growing that the violence that flared on Monday could spiral out of control, the United States is sending an envoy, Hady Amr, to the region. But efforts to end the worst hostilities in years appear so far to have made no progress.
In renewed air strikes on Gaza, Israel struck a six-storey residential building in Gaza City that it said belonged to Hamas, the Islamist group that controls the Palestinian enclave.
At least 83 people have been killed in Gaza since violence escalated on Monday, medics said.
"We are facing Israel and Covid-19. We are in between two enemies," said Asad Karam, 20, a construction worker, standing beside a road damaged during the air strikes. An electricity pole had collapsed by the road, its wires severed.
In the latest Palestinian rocket attacks, one rocket crashed into a building near Israel's commercial capital of Tel Aviv, injuring five Israelis, police said. Sirens blared in cities across southern Israel, sending thousands running for shelters.
Seven people have been killed in Israel, its military said.
Israel has prepared combat troops along the Gaza border and was in "various stages of preparing ground operations", a military spokesman said, a move that would recall similar incursions during Israel-Gaza wars in 2014 and 2008-2009.
‘A senseless civil war’
Israel’s president has warned the country is descending into a “senseless civil war” amid a growing wave of street violence.
Reuven Rivlin interrupted a TV broadcast with an appeal to “please stop the madness”.
“We are endangered by rockets that are being launched at our citizens and streets, and we are busying ourselves with a senseless civil war among ourselves,” said the president.
It came as footage showed what was described as “near-lynchings” of Jewish and Arab motorists.
In one shocking incident shown live on TV, a mob was seen dragged a man they thought was an Arab from his car in a Tel Aviv suburb and beating him until he lay motionless and bloodied on the ground.
A synagogue and cars were torched in the city of Lod, motorists were stoned on some roads, and Palestinian flag-waving protesters clashed with police in northern Haifa port.
In Lod, police imposed a rare night-time curfew, but Israeli media showed young Jewish men - some with bats - on the streets.
In a video statement, Prime Minister Benjamin Netanyahu pledged to grant police emergency powers to crack down on the mobs.
“This violence is not who we are,” he said. “I don’t care if your blood’s boiling.”
“It is important for both sides to take a step back,” he told Sky News.
“We have seen however an unprecedented level of rocket attack into Israel,” he said. “We want to see the rocket attacks stop.”
President Joe Biden, speaking after a phone call with Mr Netanyahu, said: “Israel has a right to defend itself against thousands of rockets flying into their territory.
He added: “My hope is that we’ll see this coming to a conclusion sooner rather than later.”