JERUSALEM (AP) — The Israeli army said it launched an offensive operation early Tuesday against the Gaza Strip to quell rocket attacks, and a Palestinian official said Israeli airstrikes injured at least nine Palestinians.
The Israeli airstrikes come after Gaza militants fired dozens of rockets at southern Israel on Monday, setting off air raid sirens and forcing hundreds of thousands of Israelis to stay indoors.
The military rushed more forces to the border late Monday and had warned that such an offensive was likely.
A Twitter statement from the Israeli army said the offensive, dubbed "Operation Protective Edge," is intended to "stop the terror Israel's citizens face on a daily basis."
The army said it was carrying out airstrikes in the Gaza Strip early Tuesday. It did not elaborate.
Gaza health official Ashraf Al-Kedra said at least nine Palestinian civilians were brought to a Gaza hospital with light to moderate injuries from the airstrikes, including several who suffered from shock. He said some of the injured Palestinians were treated and released.
The latest violence came as Israel pressed forward with its investigation of six Jewish youths suspected of abducting and killing a Palestinian teenager, and Israeli leaders sought to calm an emotional debate over whether the country's politically charged atmosphere led to the gruesome crime. An Israeli official said three of the youths had confessed to the attack.
Tensions have been high since three Israeli teenagers kidnapped June 12 in the West Bank were later found dead, followed by last week's slaying of the Palestinian youth in what many suspect was a revenge attack. Throughout the unrest, Gaza militants have launched more than 200 rockets and mortars into Israel, including close to 100 on Monday alone.
Israel has responded with dozens of airstrikes, but has not been able to halt the attacks. Eight Palestinian militants were killed in fighting Monday, the highest death toll yet.
The army said at least 70 rockets were fired at Israel from Gaza on Monday, including 40 launched in a single hour after nightfall, setting off air raid sirens up to 50 miles (80 kilometers) from Gaza, the military said.
Twelve rockets were intercepted by rocket-defense batteries, it added, while the others landed in open areas. It was the deepest penetration of rocket strikes in the current round of fighting and raised the likelihood of an even tougher Israeli response.
The army later said that eight more rockets and mortars were fired at Israel from Gaza starting shortly before midnight and into early Tuesday, and an additional rocket was intercepted above the Israeli town of Sderot, close to the border with Gaza.
Maj. Gen. Yoav Mordechai, a senior military official, gave a special interview in Arabic to Al-Jazeera, warning that Hamas would bear the consequences for the escalation.
Among the dead were six Hamas militants who Israel said were killed in an accidental blast in a tunnel packed with explosives. Hamas, the Islamic militant group that controls Gaza, vowed revenge, saying "the enemy will pay a tremendous price."
Lt. Col. Peter Lerner, an Israel Defense Forces spokesman, had said the army was moving more infantry forces to the Gaza border and had received authorization to mobilize up to 1,500 reservists.
The deaths of the Hamas militants had made a "substantial influence" on the situation, he said.
"There is a potential of deterioration due to their death. Therefore the IDF has to continue to reinforce capabilities in the south, with the potential that things could escalate further," he said.
Israeli security officials had said late Monday that Israel was leaning against a massive operation and would likely increase the pressure gradually with stronger and more numerous retaliatory attacks. They spoke on condition of anonymity because they were not authorized to discuss internal military deliberations with reporters. Israeli Cabinet ministers voted in favor of more intense airstrikes, Channel 2 TV said.
In Washington on Monday, State Department spokeswoman Jen Psaki said the U.S. condemns the rocket fire. "We also support Israel's right to defend itself against these attacks," she said.
President Barack Obama called for Israelis and Palestinians alike to show restraint and put an end to acts of retribution, in some of his first public comments on the matter since the murder of three Israeli teenagers touched off a new round of violence and deepening mistrust.
In an op-ed published in the Israeli newspaper Haaretz, Obama called it a "dangerous moment" for the region where a vaunted U.S. peace effort recently collapsed. Writing in emotional terms, he said he couldn't imagine the pain suffered by the parents of the three Israeli teens, but was also heartbroken by the senseless murder of a Palestinian teenager who many suspect was killed in revenge.
"All parties must protect the innocent and act with reasonableness and restraint, not vengeance and retribution," Obama said.
Obama's comments — published in Hebrew, Arabic and English — reflected growing U.S. concern about tit-for-tat violence spiraling out of control as the fragile situation in Israel appears to deteriorate.
After the bodies of the three Israelis were discovered, Obama issued a brief written statement, but hasn't spoken about the situation publicly. Haaretz said the op-ed published late Monday was intended for the newspaper's upcoming peace summit and written before June 30, the day the three Israeli teens were found dead. But it referenced events that occurred later, suggesting the op-ed was updated.
Obama also offered strong praise for Palestinian President Mahmoud Abbas, who is under pressure as Israel seeks to use the murder of the three Israelis to discredit his newly formed unity government with Hamas.
"In President Abbas, Israel has a counterpart committed to a two-state solution and security cooperation with Israel," Obama said. He offered no parallel praise for Israeli Prime Minister Benjamin Netanyahu.
During the day Monday, lines of Israeli tanks and buses were gathered near the border area as soldiers milled about. Late Monday, with roads in southern Israel all but empty, a flatbed truck carrying an armored vehicle made its way toward the border area.
Israel has launched two broad military operations in Gaza in the past five years, most recently in 2012, when eight days of heavy fighting ended in an Egyptian-mediated truce.
The increased rocket fire followed the killing of Mohammed Abu Khdeir, a 16-year-old Palestinian boy from east Jerusalem who was abducted and burned to death last week.
Israeli officials Sunday announced the arrests of six Jewish youths in the killings - ruling out earlier theories that criminal activity or personal reasons might have been a factor. They said the suspects, including some minors, were from the Jerusalem area.
Abu Khdeir's death triggered several days of violent protests in Arab areas of Jerusalem and northern Israel as Palestinians accused Israeli extremists of killing the boy to avenge the earlier deaths of the Israeli teens.
Israel's Shin Bet agency, which handles top security cases, imposed a gag order, blocking key details, including the identities and backgrounds of the youths, as well as most of the evidence from being made public.
An Israeli official said three of the youths had confessed to the crime and even re-enacted it for authorities. The official spoke on condition of anonymity due to the gag order.
The official said the suspects included two brothers, and that one of the suspects is the son of a rabbi. Three minor suspects were allowed to meet with lawyers Monday, while the primary suspects were not.
Naftali Werzberger, a lawyer for one of the suspects, said he didn't even know what his client looked like, adding that the young man was prohibited from receiving details that he is being represented by a lawyer.
"The families are in shock," Werzberger added. "No one among the suspects has a violent past or tendency and they can't explain how we got to this point where their children were arrested as suspects for acts that are very, very serious."
Despite the gag order, some additional details have begun to emerge.
Israel's Channel 10 TV said the suspects were the son and five grandsons of a prominent rabbi in Jerusalem, without further identifying him. It said two suspects used the rabbi's car for the kidnapping without his knowledge. It added that a Jerusalem district court presented its suspicions Monday against the suspects, including "belonging to a terror organization." It did not elaborate, and Israeli officials did not confirm the details in the report.
The news that the suspects were Jewish set off nationwide soul-searching over how Israelis could possibly carry out such a gruesome crime. A preliminary autopsy found that Abu Khdeir was still alive when he was set on fire.
"I am ashamed on behalf of my nation and grieve with you," President Shimon Peres told Abu Khdeir's father, Hussein, in a phone call. "The only thing left for all of us to do is to ensure that no more children are murdered, and no more tears are shed by mothers."
Peres, a Nobel Peace laureate, was among top Israeli officials, including Prime Minister Benjamin Netanyahu, who reached out to the family in person or by telephone.
Netanyahu, who has condemned Abu Khdeir's death and tried to calm the public, said he had expressed his condolences to the family.
"I would like to express my outrage and that of the citizens of Israel over the reprehensible murder of your son," a statement quoted Netanyahu as saying.
Rachelle Fraenkel, the mother of one of the slain Israeli teenagers, said that even from the "abyss" of her own pain, she could not describe her distress over the killing of the Arab boy.
"No mother and father should endure what we are going through now. We feel the pain of Mohammed Abu Khdeir's parents," she said.
Also Monday, Israeli police said a border policeman had been temporarily suspended from special operations and transferred to a different position until the completion of an investigation into the apparent police beating of Tariq Abu Khdeir, a Palestinian-American teenage cousin of the murdered Palestinian youth.
Despite his home detention, Tariq Abu Khdeir traveled to the West Bank town of Ramallah to meet President Mahmoud Abbas.
Associated Press writer Josef Federman contributed to this report.