On Friday the Israeli military boosted forces in the area to search for the suspects, described by a spokesman as "two masked terrorists," and to attempt to prevent any escalation in violence. The Palestinian group Hamas, which rules the Gaza Strip and still has a presence in the West Bank, called for revenge.
Ibrahim Dawabsheh, a Duma resident, said he heard people shouting for help from the house and rushed to it. "I saw two masked men outside," he told Reuters. He went to get help, and when he returned they had gone.
"We found the parents outside with burns. They said there was another son in the house. We brought him out and then they said there was another boy inside, but we couldn't reach the bedroom because of the fire. He was left inside until rescue forces came," Dawabsheh told Reuters.
Pictures circulated by Palestinian media on the Internet showed a smiling boy named Ali Dawabsheh. Footage from the house showed blackened walls and singed family photos scattered across charred belongings.
Israeli Prime Minister Benjamin Netanyahu said he was shocked, and promised that "all means" would be used to bring the assailants to justice. "This is a terrorist attack. Israel takes firm action against terrorism, no matter who its perpetrators are," he said.
Part of Netanyahu's right-wing coalition is the ultranationalist Jewish Home party, which advocates more settlements and settler rights in the West Bank. Jewish Home leader Naftali Bennett was quick to denounce the attack, but Palestinians accused the party of laying the ground for it.
Israeli military spokesman Lt.-Col. Peter Lerner called the arson "nothing short of a barbaric act of terrorism."
The police said a special task force was investigating the killing, along with the Shin Bet security service.
Earlier a spokesman for Abbas held Israel responsible. "Such a crime would not have occurred if the Israeli government did not insist on pursuing settlements and protecting settlers," Nabil Abu Rdainah said.
Hamas spokesman Hussam Badran called for retaliation. "This crime has made occupation soldiers and settlers everywhere legitimate targets," he said.
Fearing the killing would provoke violence in Jerusalem, police restricted entrance to the Al-Aqsa mosque for Friday prayers to men over the age of 50 and to women, a restriction that Israel often places upon the Holy Esplanade due to security concerns.
Some stone-throwing erupted outside the Old City, police said, with one officer lightly injured. In the West Bank city of Hebron, stone-throwing clashes between hundreds of Hamas supporters and Israeli soldiers broke out after prayers.
Israeli Police spokeswoman Luba Samri said the torching appeared to have been a "Price Tag" attack, a reference to militant settlers who exact retribution for any Israeli government curbs on settlement expansion in the West Bank.
Israel tore down two illegal structures in the Beit El settlement near Ramallah and removed dozens of people from another settlement near Nablus on Wednesday, prompting protests.
But in order to placate his right-wing coalition partners, Netanyahu also approved the “immediate construction,” also on Wednesday, of 300 housing units in the very same settlement, as well as advancing plans for 504 new housing units in Israeli settlement areas in East Jerusalem.
The "Price Tag" group has been blamed for torching a number of mosques in the West Bank in recent years. Those attacks caused widespread damage but no casualties.
Israel has promised to crack down on such assailants, though only a handful of indictments have been handed down.
The Palestinians seek a state in the West Bank, East Jerusalem and the Gaza Strip. In the West Bank, they have limited self-rule, but nearly 60 percent of the territory remains under the full control of the Israeli military.
Israeli settlements are considered illegal under international law. The last round of U.S.-brokered peace talks between Israel and the Palestinians broke down in 2014.
Al Jazeera and Reuters