Israel reckoned with rising homegrown extremism Sunday as it arrested six Jewish suspects who are believed to have burned to death an Arab teenager in revenge for the killing of three Israeli teens.

The arrests shocked those on both sides of the Israeli-Palestinian divide — Palestinians because many had assumed Israel would never act against its own, and Israelis because there had been widespread doubt that Jews could have carried out such a heinous crime.

Sunday’s action could help defuse what has been seen as a dangerous swelling of Palestinian anger, with violent protests in East Jerusalem and Arab towns in northern Israel feeding fears of a budding intifada. Demonstrators who have called for an uprising against the Israeli occupation have decried the lack of justice and had bitterly predicted that 16-year-old Mohammad Abu ­Khieder’s killers would never face trial.

But by arresting the suspects, who were said by security officials to have killed Khieder for ­“nationalistic” reasons, the Israeli government must confront ­extremist elements within its ­society.

Human rights advocates have long warned of an alarming rise in anti-Arab vandalism and vigilante attacks carried out by Jewish extremists. Such incidents are referred to by their perpetrators as the “price tag” for what they see as Israeli government concessions to the Palestinians.

But Khieder’s killing Wednesday went far beyond most such attacks in its raw brutality. Some Israeli officials had speculated that the slaying was a result of a family dispute amid disbelief that it could have been revenge for the deaths of the three Israelis.

“This a shock for most Israeli Jews, and I think it’s a kind of wake-up call,” Israeli Justice Minister Tzipi Livni said in an interview Sunday evening. “This is something that will change the way people think, and it will lead to a better understanding that we need to act when we see even the smallest signs of incitement, whether it is on Internet sites or price-tag attacks.”

Livni said the conflict is “not just between the Israelis and the Palestinians, it is within Israel between different Israeli citizens, and this is what worries me the most.”

Visiting the home of one of the Israeli teens slain last month after being abducted in the West Bank, Israeli Prime Minister Benjamin Netanyahu said Khieder’s killers would “face the full weight of the law.”

But he also called on the Palestinian Authority, which controls some areas of the West Bank, to go after the killers of the Israelis — 16-year-old Naftali Fraenkel, 16-year-old Gilad Shaar and 19-year-old Eyal ­Yifrach. Israel blames the killings on the Palestinian militant group Hamas, and the assailants are thought to ­remain at large.

“I know that in our society, the society of Israel, there is no place for such murderers,” Netanyahu said. “And that’s the difference between us and our neighbors. They consider murderers to be heroes.”

Palestinians counter that ­Israelis attack Arabs with impunity and that Israeli authorities do not do nearly enough to combat hate crimes or rein in security forces.

Hussein Abu Khieder, Mohammad’s father, said Sunday that he believed Israel had acted against his son’s alleged killers only because of international pressure.

Regardless of the reason, he said, he welcomed the arrests and expressed hope that they represent a broader change in Israeli attitudes toward crimes against Palestinians.

“It is not like it used to be. They can’t get away with it anymore,” he said. “In the past, if Israelis did something to the Palestinians they could get away with it. But this time it’s not like that. I think the Israeli government is embarrassed by this.”

Authorities did not immediately release the names of those arrested Sunday, citing a legal order that bars them from commenting publicly on certain details of the investigation.

Police spokesman Micky Rosenfeld said the suspects were also suspected of possible involvement in the attempted kidnapping last week of a Palestinian boy who had been standing with his mother in the prosperous East Jerusalem neighborhood of Shuafat.

Khieder was abducted in the same area the following day as he waited outside a mosque for dawn prayers. By the time his body was found later that morning, 90 percent of it was covered in burns.

Eran Schwartz, a spokesman for the legal aid organization Honenu, said the six suspects range in age from 16 to 25 and come from Jerusalem neighborhoods as well as West Bank settlements.

They were arrested early Sunday by police wearing civilian clothes who burst into their homes and apprehended them using stun guns, Schwartz said.

Honenu, which Schwartz said will help represent the suspects, describes itself on its Web site as an organization that defends “soldiers and civilians who find themselves in legal entanglements due to defending themselves against Arab aggression, or due to their love for Israel.”

The outrage over Khieder’s killing has left in its wake new sources of grievance.

Palestinians were particularly incensed in recent days by the emergence of a video apparently showing plainclothes Israeli security officers pummeling one of Khieder’s cousins, who is a high school student from Florida. Subsequent images showed Tariq Abu Khieder’s face bruised and bloodied.

Khieder, 15, was sentenced Sunday by an Israeli court to nine days of house arrest after Israeli officials accused him of being among a group of Palestinians who were throwing pipe bombs and firecrackers at police during protests in Shuafat.

In an interview, Khieder denied that and said the officers ambushed him. “They pushed me down on the ground and beat the hell out of me,” said Khieder, whose eyes and mouth were still badly bruised. “I went into a coma, and the next thing that happened, I woke up in the hospital.”

Israel’s Justice Ministry said Sunday that it had launched an investigation into possible police brutality. The State Department later issued a statement calling for “full accountability for the apparent excessive use of force.”

In a suggestion that frustration remained high among Palestinians despite Sunday’s arrests, there were reports late in the evening of fresh protests, with Palestinians allegedly throwing rocks and attempting to block a major highway.

Meanwhile, rocket fire from militants in the Gaza Strip continued unabated after Israel carried out 10 airstrikes early Sunday. The Israeli army said at least 20 rockets had landed in southern Israel by 8 p.m., though there were no reported injuries. The military announced before midnight that it had carried out airstrikes on Gazan rocket launchers. The armed wing of Hamas said seven of its gunmen were killed, Reuters reported.

But amid talks to revive a tattered cease-fire, Netanyahu said there would be no sharp escalation from the Israeli side — at least not now.

“Experience proves that in moments like these, one must act calmly and responsibly, not hysterically and hastily,” he said.

There were other signs Sunday that after weeks of wrenching pain over the deaths of teenagers on both sides of the conflict, Israeli-Palestinian hostilities may be easing, if only slightly.

Yishai Fraenkel, uncle of slain Israeli teen Naftali Fraenkel, said in an interview that his family had received many condolence calls from Palestinians in recent days. On Sunday he spoke by phone to Hussein Abu Khieder and extended the Fraenkel family’s sorrow at the death of Khieder’s son, Mohammad.

“I told him that all murderers need to be caught and punished for these crimes,” Fraenkel said.

Witte reported from London.