NYT summarizes the signficance and scale of the attack:
Israel battled on Saturday to repel one of the broadest invasions of its territory in 50 years after Palestinian militants from Gaza launched an enormous and coordinated early-morning assault on southern Israel, infiltrating several Israeli towns and army bases, kidnapping Israeli civilians and soldiers, and firing thousands of rockets toward cities as far away as Jerusalem.
By early evening, the Israeli military said fighting continued in at least five places in southern Israel, at least 100 Israelis had been reported dead by emergency medical groups, and Israel had retaliated with huge strikes on Gazan cities. At least 198 Palestinians were killed in either gun battles or airstrikes, the Gazan Health Ministry said.
The Hamas militants behind the attack also took Israelis hostage, the chief spokesman for the Israeli military, Rear Adm. Daniel Hagari, said.
In an assault without recent precedent in its complexity and scale, the militants crossed into Israel by land, sea and air, according to the Israeli military, leading to some of the first pitched battles between large groups of Israeli and Arab forces on Israeli soil in decades. As of early evening there were the two main battles taking place, near the towns of Ofakim and Beeri, Admiral Hagai said. After a brief lull in rocket launches, Palestinian militants fired an evening barrage at Israeli towns and cities in the country’s central heartland, the Israeli military said, setting off red alert sirens and sending scores of Israelis fleeing for shelter.
All told, the Israeli military said that the militants had entered at least 22 Israeli towns, abducting soldiers and civilians, including an older grandmother. Residents of Israeli border towns told broadcasters that gunmen were moving door to door, looking for civilians. Unverified footage appeared to show Palestinian fighters transporting captured Israeli civilians and bodies through the strip.
“We are at war and we will win it,” Prime Minister Benjamin Netanyahu of Israel said in a televised statement, announcing a call-up of Israeli military reservists.
