Israeli leaders vowed to find the suspected Israeli extremists behind an arson attack that killed a Palestinian toddler early Friday.

We reported Friday that the attack killed the 18-month-old boy and wounded four of his family members — some critically.

The injured were flown to an Israeli hospital where Prime Minister Benjamin Netanyahu visited one of the toddler's brothers, who he said suffered burns over 60 percent of his body.

"We're shocked, we're outraged," Netanyahu said in a video posted by his office. "There's zero tolerance for terrorism wherever it comes from, whatever side of the fence it comes from we have to fight it and fight it together."

The attack occurred before dawn in the West Bank village of Duma. Two houses were burned and perpetrators spray-painted the walls with Hebrew words, including "revenge."

Suspicion turned quickly toward Jewish settlers, usually youth, who have committed so-called "price tag" attacks. These are attacks against Palestinians to make them pay when the Israeli government takes actions seen as harming settlers' interests — like when Israel this week carried out a court order and demolished buildings in a Jewish settlement. Also, as one Israeli official pointed out, an Israeli was killed 30 days ago near the location of Friday's arson.

The attack could push the issue to a higher level of Israeli concern. "I think that what we are having here is a defining moment for the Israeli public," said Israeli political science professor Yaron Ezrahi.

Ezrahi noted that Israeli leaders quickly labeled the perpetrators "terrorists," a term they usually apply to Palestinian attackers. He said they realize that this kind of extreme violence "can consume this society from inside."

Palestinians have long called for Israel to do more to prevent violence by Jewish settlers, who live in the Israeli-occupied West Bank. They blamed Israel for the most recent attack. Palestinian Authority President Mahmoud Abbas called it a "war crime." And long-time Palestinian negotiator Saeb Erekat said the attack was "a direct consequence of decades of impunity given by the israeli government to settler terrorism."

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