Named Operation Pillar of Defense (in Hebrew, Operation Pillar of Cloud), the intense aerial strikes also targeted Hamas rocket arsenals throughout the Gaza Strip.
Hamas responded with heavy rocket fire into Israel, and the IDF deployed infantry brigades to the Gaza border ahead of a possible ground offensive.
The first wave of air strikes killed eight Palestinians, Palestinian sources said.
As 90 rockets exploded across southern Israel on Wednesday night, schools within 40 km. of the Gaza Strip were declared closed, and residents were urged to follow directives from the IDF Home Front Command. The Iron Dome rocket defense system intercepted 29 rockets.
Schools and universities will be closed in the South on Thursday from Beersheba to Ashdod.
Gaza-border communities are in lockdown, with residents ordered to remain in their homes if they live within 7 km. of Gaza.
Explosions have been reported as far away as Dimona, some 75 km. from the Gaza Strip.
At an emergency meeting in Tel Aviv, the security cabinet authorized Defense Minister Ehud Barak to mobilize reservists if needed.
The cabinet also agreed that the IDF should continue to act against terrorist infrastructure and activity in Gaza. It instructed the Foreign Ministry to begin a diplomatic public relations campaign to explain that Israel was acting in self-defense against military targets, because the continued rocket barrage had become intolerable.
Prime Minister Binyamin Netanyahu spoke on the telephone on Wednesday night with US President Barack Obama, Vice President Joe Biden and EU foreign policy chief Catherine Ashton. He was also scheduled to speak with UN Secretary-General Ban Kimoon.
The prime minister thanked Obama and Biden for taking the position that Israel had a right to defend itself.
But Barak and Netanyahu held a joint press conference to explain that they had no choice.
“Today we relayed a clear message to the Hamas organization and other terrorist organizations,” Netanyahu told reporters. “And if there is a need, the IDF is prepared to broaden the operation. We will continue to do everything in order to protect our citizens.
Barak said, “We are still at the beginning of the event, not at the end, and we expect some complicated tests ahead. It will require vigilance; not only in Gaza, but also in Israel and in Judea and Samaria. But in the long run I believe that this operation will contribute to strengthening deterrence and reinstituting the calm in the South.”
He added that the operation was designed to damage rocket- launching networks, deliver a “painful blow” to Hamas and other terrorist organizations, and protect the home front.
On Tuesday, it had appeared as if an uneasy calm had been restored. Barak and Netanyahu helped to strengthen that impression, by traveling to the North and talking about Syria, even as they gave the final authorization for Wednesday’s targeted killing.
The operation began at 4 p.m. over Gaza City, where a missile hit a car carrying Hamas armed wing chief Jabari, killing him and a second man. Conflicting reports emerged over whether the second casualty was Jabari’s bodyguard or his son. An air strike in southern Gaza killed a second senior Hamas man.
The IDF warned all terrorists in Gaza to remain underground if they wished to live.
The strikes were accompanied by a series of sorties targeting underground launchers loaded with long-range Hamas missiles that can reach more than 40 km. away from Gaza, such as Fajr missiles. The air strikes eliminated most of Hamas’s long-range capabilities, the IDF believes.
“The first aim of this operation is to bring back quiet to southern Israel, and the second target is to strike at terrorist organizations,” IDF spokesman Brig.-Gen. Yoav Mordechai said. “The home front must brace itself.”
He described Jabari as a man with “a lot of blood on his hands,” and Gaza as a “forward Iranian base” where terrorist factions had spent years building up a rocket arsenal.
“This is the beginning of the operation,” Mordechai warned. “All options are available,” he added, alluding to the possibility of a ground incursion.
Hamas warned that “the gates of hell had opened,” as it struggled in the first few hours after the strikes to regain its footing. As the evening drew on, the Hamas regime fired increasing numbers of rockets across the border into southern Israel
Following the Hamas attacks, the IDF struck dozens of underground rocket launchers loaded with medium-range projectiles that can reach as far as 40 km.
Israel Navy ships also fired at Hamas terrorist targets along the Gaza coast.
Prior to the operation, IDF Chief of Staff Lt.-Gen. Benny Gantz spent two days finalizing its details, as the defense minister repeatedly visited the Gaza Division to go over the plans.
Most of the Gaza weapons storage sites targeted by the Israel Air Force were located in civilian residential buildings.
“This is further evidence of Hamas’s pattern of using the population in Gaza as human shields,” an IDF source stressed.
Before the operation was launched, four rockets – believed to have come from Egypt’s Sinai Peninsula – exploded in the Eshkol region.
The operation came after Hamas and Islamic Jihad fired 128 rockets into southern Israel earlier this week.
“We strongly condemn the barrage of rocket fire from Gaza into southern Israel, and we regret the death and injury of innocent Israeli and Palestinian civilians caused by the ensuing violence. There is no justification for the violence that Hamas and other terrorist organizations are employing against the people of Israel,” the US State Department said.
“We call on those responsible to stop these cowardly acts immediately. We support Israel’s right to defend itself, and we encourage Israel to continue to take every effort to avoid civilian casualties,” it said.