Witnesses said Jabari was traveling in a vehicle in Gaza City when the car exploded. Crowds of people and security personnel rushed to the scene of the strike, trying to put out the fire that had engulfed the car and left it a charred shell. The Israeli military released a grainy, black-and-white video of the airstrike. It shows a sedan moving slowly along a road before exploding in a powerful blast that sent a large piece of the car flying into the air.
Fearing a long war in Gaza, Palestinians rushed to buy fuel, bread and other food supplies.
"We are working under fire to protect our people and to back the resistance," said Islam Shahwan, a Hamas interior ministry spokesman. "We have a full emergency plan that we are adopting now."
The chief military spokesman, Brig. Gen. Yoav Mordechai, said "at this stage" there are no plans for a ground offensive. "We're focusing on an air operation," he said. The military said the assassination was just the beginning of an operation codenamed "Pillar of Defense."
"After a couple of days on ongoing rocket attacks toward Israeli civilians, the (Israeli military) chief of staff has authorized to open an operation against terror targets in the Gaza Strip," military spokeswoman Lt. Col. Avital Leibovitch said.
She said Jabari had "a lot of blood of his hands" and that the military chief "authorized different targets" as well.
Advocates say targeted killings are an effective deterrent without the complications associated with a ground operation, chiefly civilian and Israeli troop casualties. Proponents argue they also prevent future attacks by removing their masterminds.
Critics say the killings invite retaliation by militants and encourage them to try to assassinate Israeli leaders. They complain that the strikes amount to extrajudicial killings.
Dovish Israeli lawmaker Dov Hanin condemned the killing.
"Assassinating leaders is never the solution. In place of the leaders killed, other will grow, and we will only get another cycle of fire and blood," he said.
During a wave of suicide bombings against Israel a decade ago, the country employed the tactic to eliminate the upper echelon of Hamas leadership. During that period, Israeli aircraft assassinated the previous commander of Hamas' military wing, Salah Shehadeh, the movement's founder and spiritual leader, Sheik Ahmed Yassin, his successor, Abdel Aziz Rantisi, and dozens of other Hamas military commanders.
That set off a wave of criticism from rights groups and foreign governments, particularly the strike that killed Shehadeh — a one-ton bomb that killed 14 other people, most of them children.
Israeli opposition leader Shaul Mofaz, a former chief of staff who has supported targeted killings, welcomed the strike.
"We need to continue this policy, to find them in every place," he told Israel's Army Radio. "Israel needs to determine the agenda, not Jabari."
Mofaz warned that Israelis should expect an escalation of violence in the coming days following the assassination.
Anticipating more Hamas retaliation, the military issued instructions to its citizens in southern Israel to stay close to home. School was cancelled for Thursday in southern Israel.
President Shimon Peres updated President Barack Obama on the developments.
"Jabari was a most extreme man and was responsible for all the attacks and assassinations from Gaza against Israel," Peres told Obama. "We shall handle it with great care. Our intension is not to raise the flames, but already for days, day and night, they are shooting rockets at Israel."
Jabari was known in Israel as the man who accompanied Schalit when the high-profile prisoner swap took place last October. Schalit, who was captured in a cross-border raid from Gaza that killed two other soldiers, was swapped for more than 1,000 Palestinian prisoners, including more than 300 convicted killers.
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