- "Israeli planes and troops on the ground are carrying out an attack in the Gaza Strip," the Israeli army said in a brief message.
Israel said Friday it sent ground forces into action and pounded Gaza in response to a new barrage of rocket fire from the Hamas-run enclave in a conflict that has now claimed over 100 Palestinian lives.
"Israeli planes and troops on the ground are carrying out an attack in the Gaza Strip," the Israeli army said in a brief message.
The escalation was confirmed by army spokesman John Conricus, although he did not specify the scale of the operation.
As the violence intensified, Israeli security forces scrambled to contain deadly riots between Jews and Arabs, with projectiles also fired on Israel from Lebanon.
US Secretary of State Antony Blinken said Washington was "deeply concerned about the violence in the streets of Israel", voicing support for a United Nations Security Council meeting "early next week" on the crisis.
"We believe that Israelis and Palestinians deserve equal measures of freedom, security, dignity and prosperity," Blinken said.
There were intense artillery exchanges Thursday night, and AFP reporters saw Israeli troops assembling at the security barrier.
Balls of flames rose high into the sky after strikes smashed into densely packed Gaza.
Dozens of rockets were fired from Gaza towards the southern Israeli coastal cities of Ashdod and Ashkelon, and in the vicinity of Tel Aviv's Ben Gurion airport.
"We are prepared, and continue to prepare for various scenarios," Conricus said, describing a ground offensive as "one scenario".
In Gaza, AFP photographers said people were evacuating their homes in the northeastern part of the enclave ahead of possible Israeli attacks, with Hamas, the Islamist group that controls Gaza, warning of a "heavy response" to a possible ground incursion.
- 'Massive reinforcement' -
With the conflict showing no signs of easing, Israel has been rocked by an unprecedented wave of mob violence, in which both Arabs and Jews have been savagely beaten and police stations attacked.
Defence Minister Benny Gantz ordered a "massive reinforcement" to suppress the internal unrest.
The heavy bombardments coincided with the start of Eid al-Fitr, which marks the end of the Muslim holy fasting month of Ramadan, and saw the faithful pray at mosques and amid the rubble of Gaza's collapsed buildings.
Israel's air force launched multiple airstrikes, targeting locations linked to Hamas, with the air force saying jets had struck a "military compound" of the group's "intelligence headquarters".
At least 103 people have been killed since Monday, including 27 children, and more than 580 wounded, the health ministry in Gaza said.
Heavy bombardments have brought down entire tower blocks.
Inside Israel, seven people have been killed since Monday, including one six-year-old, after a rocket struck a family home.