Jerusalem - The Israeli army said it launched an offensive operation early on 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 on 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 on 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 12 June 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.
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.