Israeli war planes slammed dozens of targets Thursday in air raids against militants in the Gaza Strip, a day after an Israeli missile strike on Gaza killed the top military commander of Hamas.
Barrages of rockets were fired back at Israel from Gaza with one strike killing at least three Israelis in an apartment complex, bringing the combined death toll on both sides to 15.
VOA's Jerusalem correspondent Scott Bobb in southern Israel said three units of the apartment block were destroyed. Residents in the area are staying indoors in anticipation of more attacks, said Bobb.
Sirens also went off late Thursday in Tel Aviv sparking a panic and nearly crippling mobile phone service after missiles fired from Gaza approached the city.
Israeli officials say the missiles fell into the sea. Palestinian militants issued a statement claiming responsibility, saying they had fired Iranian-made rockets. It is the first time sirens have sounded in Tel Aviv since the Gulf War in 1991.
Israeli security officials are warning residents to seek protection in reinforced bomb shelters or in public institutions when they hear sirens.
Schools in southern Israel are closed and many businesses within 40 kilometers of the Gaza border are not opening Thursday for fear of shelling by Palestinian militants.
Watch related video:
Inside the Gaza Strip, Palestinians too were taking cover, going out only to get staples. Israel dropped leaflets warning Gazans to stay away from buildings and locations run by the military wing of Hamas.
Palestinian officials say the latest Israeli strikes killed two people Thursday, including a child, bringing the Palestinian death toll over the past two days to 12. Hamas military commander Ahmed al-Jaabari was killed Wednesday in an Israeli airstrike.
Israel's Shin Bet intelligence service said Jaabari was killed because of his "decade-long terrorist activity," including the kidnapping of Israeli soldier Gilad Shalit in 2006. Jaabari was the most senior Hamas official to be killed since an Israeli invasion of Gaza four years ago.
Hamas warned Israel had opened up what it calls "the gates of hell" and vowed revenge.
Top Palestinian official Saeb Erekat said the situation was "very grave."
"We are doing, exacting, every possible effort in order to have the situation de-escalated, because I think it is in nobody's interest to see this assassination, attack against [Ahmed] al-Jaabari, and bombardment, which we condemn in the strongest possible terms," he said.
But Israeli Prime Minister Benjamin Netanyahu said Israel would not allow Hamas to continue to terrorize its people.
“In the past 24 hours, Israel has made it clear that it will not tolerate rocket and missile attacks on its civilians. I hope that Hamas and the other terrorist organizations in Gaza got the message. If not, Israel is prepared to take whatever action is necessary to defend our people.”
World leaders are expressing concern over the escalation in violence, warning it could have dire consequences for the region.
Egyptian President Mohamed Morsi said Israeli aggression against Gaza is "unacceptable."
But U.S. Secretary of Defense Leon Panetta told VOA Thursday that he understands the reasons Israel is taking action. He said Israel has been hit by about 800 rockets or missiles this year, so he understands that Israel’s reasons for defending itself.
Panetta added that he hoped the Israelis work to minimize the civilian deaths that are likely to occur. And Panetta said he hoped that in the end that all sides will recognize the need to get back to try to negotiate a permanent peace agreement.
Israeli military gathers
Smoke rises following an Israeli attack on Gaza City, Nov. 15, 2012.
Damage is shown to the top of a building in Kiriat Malakhi, November 15, 2012. (VOA - L. Fridmam)
A Zaka volunteer cleans blood stains from an apartment in a building that was hit by a rocket fired from the Gaza Strip, where three people were killed in Kiryat Malachi, southern Israel, Kiryat Malachi, southern Israel, November 15, 2012.
Zaka volunteers clean blood stains from a pillow and a baby toy in a children's room in apartment building that was hit by a rocket fired from the Gaza Strip, where three people were killed in Kiryat Malachi, southern Israel, Kiryat Malachi, southern Isra
Palestinian women react during the funeral of Hisham Al Galban, a Hamas militant killed in an Israeli attack, in Khan Younis, southern Gaza Strip, November 15, 2012.
A Palestinian demonstrator runs through a cloud of tear gas during clashes against Israel's operations in Gaza Strip, outside Ofer, an Israeli military prison near the West Bank city of Ramallah, November 15, 2012.
A Palestinian boy holds a window pane taken from a damaged house hit in an Israeli strike, in Gaza City, November 15, 2012.s
Israelis take cover as a siren warning of an incoming rocket sounds in Kiryat Malachi, southern Israel, Thursday, November 15, 2012.
Still, Israeli tanks and ground forces continue to gather along the border. Israeli army spokeswoman, Lieutenant Colonel Avital Leibovich, said Thursday they will be used if needed.
"All the options are on the table, including the possibility of a ground operation, we have alerted some of our reserve units and we are considering our next steps currently," she said. "We are striking various targets from the air, targets of either caches of rockets, storages of rockets, underground tunnels used to store rockets and other targets."
In Gaza, hospitals were busy treating the wounded even as thousands took to the streets for the funeral of the Hamas military commander killed Wednesday.
The head of the secret service in Gaza, Tawfeek Tirawi, accused Israel of war crimes.
"What is happening in Gaza is a crime against our Palestinian people, a continuous attack. This is part of the ongoing Israeli policies that it always attacks our Palestinian people," he said.
"Therefore, in Gaza it does not differentiate between civilians and factions," he said. "This is why we should all be one hand and end the Palestinian rift by going straight to reconciliation."
Israeli officials argue the airstrikes are a direct response to almost daily Palestinian rocket strikes on Israel and have warned Hamas members not to "show their faces above ground" in the next few days.
U.N. Security Council meets
The United Nations Security Council held a late-night emergency meeting that Egypt and council member Morocco requested on behalf of the Palestinians.
Indian Ambassador Hardeep Singh Puri, who heads the 15-nation council this month, said in his capacity as Indian ambassador that he hoped the meeting will lead to a de-escalation of violence in Gaza.
French Foreign Minister Laurent Fabius said in an interview Thursday that Israel is entitled to defend itself but urged both sides to show restraint. He said an escalation would be a "catastrophe."
VOA's Scott Bobb and Robert Berger contributed from Israel, Luis Ramirez from Bangkok, Jeff Seldin from Washington.