The army said in a statement late Thursday that after 10 days of Hamas attacks, it had "initiated a ground operation within the Gaza Strip." The army said the objective was to strike a "significant blow to Hamas' terror infrastructure."
The high-stakes move followed Israel's growing exasperation over unrelenting rocket fire and came hours after the collapse of Egyptian-led efforts to broker a cease-fire. It also followed a failed attempt by 13 militants to infiltrate Israel earlier Thursday through a tunnel under the Gaza-Israel border, only to be stopped by an Israeli strike at the mouth of the tunnel.
Israel had called up 48,000 reserve soldiers, and later Thursday the Cabinet authorized the military to call up 18,000 more, the military said.
Hamas spokesman Fouzi Barhom told reporters in Gaza, "The decision of the Israeli army to start a ground invasion in Gaza is dangerous and they will pay back heavily for it. Hamas is ready for the confrontation."
Eight Palestinians were killed in the early stage of the ground operation, including a 3-month-old boy who died after a shell hit his family's Bedouin tent in southern Gaza, The Associated Press reported, citing Gaza health officials. An Israeli soldier was killed Friday morning, though the circumstances behind his death were not immediately clear, Israel's military said.
A source with close ties to the Israeli military told Fox News, “This is not an all-out operation. ... The objectives are quite limited.”
He said the current operation, the first major Israeli ground offensive in Gaza in just over five years, is expected to last only a couple days.
"Our forces, large ground forces accompanied by massive air force support, naval forces and intelligence, are taking over targets in Gaza, operating against tunnels and terror activists and infrastructure," Israel's chief military spokesman Brig. Gen. Motti Almoz said.
He called on Gaza residents to evacuate areas where the military was operating, warning the "military is operating there with very great force."
Thousands of soldiers backed by tanks and huge DC9 bulldozers entered the Hamas-ruled territory after 10 p.m. Thursday, security officials and Israeli media said.
An official in the Gaza security operations room reported heavy Israeli tank shelling along Gaza's border areas with Israel since 8 p.m. Thursday.
"All border areas are under fire. There is a tank shell every minute," said the official, speaking on condition of anonymity in line with briefing regulations. "There is also fire from the sea toward police checkpoints."
Residents said the northern Gaza town of Beit Lahiya came under heavy Israeli shelling. "There is the sound of tank shells all the time," said Jamal Abu Samra, 42, a farmer in the area. He said his wife, six children, four brothers and their families were huddling on the ground floor of the family home.
"We don't have power since the afternoon so we are listing to the (battery-operated) radio to hear the news," he said.
He said the Israeli military sent text messages to residents urging them to leave the area. Abu Samra said he and his relatives decided to stay because they felt nowhere in Gaza is safe. "It is better to stay home than move anywhere," he said.
Prime Minister Benjamin Netanyahu's office said he instructed the army to go ahead after Hamas rejected an Egyptian cease-fire plan earlier in the week and after Hamas militants tried to infiltrate into Israel through a tunnel from Gaza earlier Thursday.
"In light of the despicable and relentless aggression by Hamas and the dangerous infiltration into Israel, Israel is obliged to protect its citizens," the statement said.
It added Operation "Defensive Edge" would continue "until its goal is reached: to restore sustainable quiet and calm to the Israeli citizens while severely hurting and dismantling Hamas infrastructure as well as other terrorist organizations in Gaza."
Lt. Col. Peter Lerner, an Israeli military spokesman, said that the operation is open-ended.
"We will be striking the infrastructure," he said. "We will be striking the operatives in order to safeguard the civilians of the state of Israel especially issues to do with tunneling, that was exemplified earlier today."
Thousands of Israeli soldiers had massed on the border with Gaza in recent days, waiting for the order to go in.
Earlier Thursday, Hamas militants and Israel exchanged rocket fire following the expiration of a brief cease-fire that allowed Gazans to stock up on supplies.
The U.N.-brokered five-hour lull in fighting gave residents of the Gaza Strip time to crowd into stores and vegetable markets after more than a week of being mostly holed up at home for fear of airstrikes. Gaza City, a virtual ghost town for the past 10 days, returned to apparent normalcy within minutes of the start of the truce. Streets were jammed, motorists honked horns and Hamas police directed traffic at busy intersections.
But the streets emptied out quickly after the cease-fire expired, with Palestinian militants firing more than 50 rockets at Israel, including a heavy salvo toward the Tel Aviv area that sent people running for cover, the Israeli military said. The military said a rocket fired from Gaza struck the city of Ashkelon at precisely 3 p.m. local time (8 a.m. ET) as the pause in military activity ended. No injuries were reported.
Israel responded with a wave of eight airstrikes, including one that killed two boys and a girl ages 8 to 10 from the same family in Gaza City, Gaza Health Ministry spokesman Ashraf al-Kidra said.