Israel pummelled Gaza with artillery fire and air strikes on Friday, killing 13 people including three children, local health officials said, as it targeted Palestinian militant tunnels to try to stop persistent rocket attacks on Israeli towns.
The largest Israeli operation against a specific target since the conflict began included 160 aircraft as well as tanks and artillery firing from outside the Gaza Strip, Israeli military spokesman Lieutenant Colonel Jonathan Conricus said.
Rocket barrages against southern Israel swiftly followed the 40-minute pre-dawn offensive on the fifth day of the most serious fighting between Israel and Gaza militants since 2014.
A woman and her three children were among 13 people killed in Gaza, health officials in the north of the enclave said, and their bodies were recovered from the rubble of their home.
An elderly woman in Israel died while on her way to a shelter to shield from the rocket attacks.
Gaza's ruling Hamas group launched the rocket attacks at Jerusalem and Tel Aviv in retaliation for Israeli police clashes with Palestinians near Al-Aqsa Mosque in Jerusalem.
At least 122 people have been killed in Gaza, including 31 children and 20 women, and 900 others wounded, Palestinian medical officials said.
Among eight dead in Israel were a soldier patrolling the Gaza border, six Israeli civilians - including two children - and an Indian worker, Israeli authorities said.
Security sources said Egypt was leading diplomacy aimed at securing a ceasefire but neither side appeared amenable so far.
The head of the International Criminal Court warned that individuals involved in the bloodshed may be targeted by its investigation into alleged war crimes in earlier bouts of the conflict.
In northern and eastern parts of Gaza, the sound of artillery fire and explosions echoed early on Friday.
The UN Office for the Coordination of Humanitarian Affairs said there were reports of more than 200 housing units destroyed or severely damaged and hundreds of people seeking shelter in schools in northern Gaza.
Israel says it makes every effort to preserve civilian life, including warning in advance of attacks.
"What we were targeting is an elaborate system of tunnels that spans underneath Gaza, mostly in the north but not limited to, and is a network that the operatives of Hamas use in order to move, in order to hide, for cover," Conricus told foreign reporters.
"We refer to (it) as the Metro," he said, adding that a final assessment on the outcome of the operation was pending.
Israeli warplanes on Friday bombed the houses of three senior Hamas military commanders in central Gaza, witnesses said. There were no reports of injuries as the dwellings had already been evacuated, local residents said.
Dozens of mourners took part in the funeral of six people - members of two families whose houses were hit by Israeli air strikes on Thursday - in the southern Gaza town of Rafah.
Holding the cloth-bound body of his 19-month-old nephew in his arms, Khamees al-Rantissi said their house was bombed without prior warning. "What was this child doing? What threat did he pose for the state of Israel?" Rantissi asked.
Israeli Prime Minister Benjamin Netanyahu said on Thursday the campaign "will take more time". Israeli officials said Hamas, Gaza's most powerful Islamist militant group, must be dealt a strong deterring blow before any ceasefire.
US President Joe Biden called on Thursday for a de-escalation of the violence, saying he wanted to see a significant reduction in rocket attacks.
Flurry of Diplomacy
Egypt is pushing for both sides to cease fire from midnight on Friday, two Egyptian security sources said, expecting further negotiations due to the high number of casualties. They said Cairo was pushing with Hamas and has asked others, including the United States, to reach an agreement with Israel.
A diplomat said an earlier ceasefire bid had failed because the Israeli side said it wanted to finish what it started and Hamas said it would not stop fighting until the Israelis did.
The hostilities have fuelled tension between Israeli Jews and the country's 21% Arab minority. Violence continued in mixed communities overnight after street fighting and tit-for-tat attacks that prompted Israel's president to warn of civil war.
"They say Gaza is spiralling out of control, but what is happening here scares me more," said Majd Abado, an Arab resident of the mixed city of Acre, where people from both communities said they were afraid to leave their homes. L1N2N0266
Israel's military said a Palestinian tried to stab a soldier near the West Bank city of Ramallah. The soldier shot the attacker. Palestinian health officials said the man was killed.
The Israeli military's build-up of forces on the Gaza border has raised speculation about a possible repeat of ground invasions during Israel-Gaza wars in 2014 and 2009. But an incursion looked unlikely, given Israel's reluctance to risk a sharp increase in military casualties on Hamas turf.
At least two owners of tankers delivering crude oil to Israel asked to divert from Ashkelon to the port of Haifa, farther north of Gaza, because of the conflict, shipping sources said on Friday. An industrial zone near Ashkelon was hit by a rocket on Tuesday, damaging a fuel storage tank.
Germany's flag carrier Lufthansa (LHAG.DE) on Friday extended its suspension of flights to Tel Aviv until May 17, while Wizz Air (WIZZ.L) cancelled all flights on Friday and Saturday, joining other airlines in avoiding Israel due to escalating conflict there.
The UN Security Council will publicly discuss the worsening violence on Sunday, diplomats said after the United States had objected to a meeting on Friday.
The Israeli military has put the number of militants killed in Israeli attacks at between 80 and 90. It said that so far, some 1,800 rockets have been fired at Israel, of which 430 fell short in Gaza or malfunctioned.