Israel has pressed ahead with its military offensive in the Gaza Strip with numerous airstrikes, while Hamas responded by launching hundreds of rockets into the country.
At least 69 Palestinians, including 16 children, have been killed in the air strikes, while seven people have died in Israel.
The air strikes toppled high-rise towers and as many as 10 senior Hamas military figures were killed in the escalating violence.
In just three days, the fighting between the bitter enemies has already begun to resemble - and even exceed - a devastating 50-day war in 2014.
The United Nations warned that tensions could boil over and become a “full-scale war”.
What’s happened in the Israel-Gaza conflict?
Israel carried out an intense barrage of airstrikes just after sunrise, striking dozens of targets in several minutes that set off bone-rattling explosions across Gaza.
Airstrikes continued throughout the day, filling the sky with pillars of smoke.
At nightfall, the streets of Gaza City were empty as people huddled indoors on the final night of Islam's holiest month of Ramadan.
The evening, followed by the Eid al-Fitr holiday, is usually a time of vibrant nightlife, shopping and crowded restaurants.
"There is nowhere to run. There is nowhere to hide," said Zeyad Khattab, a 44-year-old pharmacist who fled with a dozen other relatives to a family home in central Gaza after bombs pounded his apartment building in Gaza City.
"That terror is impossible to describe."
Nonstop rocket fire
Gaza militants continued to bombard Israel with nonstop rocket fire throughout the day and into early Thursday.
The attacks brought life to a standstill in southern communities near Gaza, but also reached as far north as the Tel Aviv area, about 45 miles to the north, for a second straight day.
The military said sirens also sounded in northern Israel's Emek area, or Jezreel Valley, the farthest the effects of Gaza rockets have reached since 2014.
"We're coping, sitting at home, hoping it will be OK," said Motti Haim, a resident of the central town of Beer Yaakov and father of two children.
"It's not simple running to the shelter. It's not easy with the kids."
16 children among those killed
Gaza's Health Ministry said the death toll rose to 69 Palestinians, including 16 children.
Islamic Jihad confirmed the deaths of seven militants, while Hamas acknowledged that a top commander and several other members were killed.
A total of seven people have been killed in Israel, including four people who died on Wednesday.
Among them were a soldier killed by an anti-tank missile and a six-year-old child hit in a rocket attack.
While United Nations and Egyptian officials have said that cease-fire efforts are underway, there were no signs of progress.
Israeli television's Channel 12 reported late on Wednesday that Prime Minister Benjamin Netanyahu's Security Cabinet authorised a widening of the offensive.
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