JERUSALEM — Protests over the killing of an Arab teenager spread to new parts of Israel early Saturday as reports emerged that he was burned alive after being abducted from his East Jerusalem neighborhood Wednesday.

The overnight protests in predominantly Arab towns of northern Israel came after a demonstration Friday in East Jerusalem by thousands of Palestinians who chanted calls for a new intifada. The fierce clashes with police that followed the teenager’s funeral stirred fears that a mass uprising could be underway.

Police spokesman Micky Rosenfeld said Saturday that 20 people were arrested in the Jerusalem clashes and 12 others were detained in the north. By midday Saturday, the demonstrations had ended, at least temporarily.

The protesters Friday waved Palestinian flags and shouted, “Enough of the suffering, enough of the pain,” capping a week that has overflowed with both for Israelis as well as Palestinians.

On Monday, soldiers discovered the bodies of three Israeli teenagers who had been missing for more than two weeks. Then, on Wednesday, the badly burned remains of 16-year-old Mohammad Abu Khieder were found in a forest.

Although no definitive link has been established between the cases, there was no doubt in the Palestinian neighborhood of Shuafat on Friday that Khieder’s killing was carried out by Jewish extremists and that it was intended as revenge.

On Saturday, Palestinian news services quoted Palestinian Attorney General Abdelghani al-Owaiwi as saying that a preliminary autopsy had discovered soot in the teen’s lungs, indicating he was still alive when he was burned. The autopsy also revealed evidence of a head wound, but the fire caused his death, Owaiwi said.

The teenager’s father, Hussein Abu Khieder, said Saturday that he had not yet seen the autopsy report and had not received any information from the police regarding possible suspects.

The killings of the teenagers have brought Israeli-Palestinian relations to their most volatile level in nearly a decade, and Friday’s running street battles between rock-throwing demonstrators and stun-grenade-firing police revived dark memories of intifadas, or uprisings, from decades past.

Continuing rocket fire from the Gaza Strip on Friday and Saturday only added to the sense of escalating tensions. Israel responded with an airstrike late Friday.

“We can’t live like this. Every day our people are killed,” said one Palestinian youth masked with a kaffiyeh, or Arab headdress, who was protesting in East Jerusalem. He said that he and his friends could see an intifada in their future, similar to the uprisings that convulsed this region in the late 1980s and early 2000s.

Others were more hopeful. The killing of Khieder “took place during a delicate situation, but I do believe it will not escalate much more than what we see today,” said Giora Eiland, former head of Israel’s National Security Council.