Scores of Israelis set dozens of cars and homes on fire in Samaria, part of the West Bank, on Sunday after two settlers were killed by a Palestinian gunman. Palestinian medics said one man was killed and four others were badly wounded in what appeared to be the worst outburst of violence in decades.

The deadly shooting, followed by the late-night unrest, immediately raised doubts about Jordan’s declaration that Israeli and Palestinian officials had pledged to calm a year-long wave of violence. The Palestinian press said some 30 homes and cars were torched. Photos and video on social media showed fires burning throughout the town of Huwara — scene of the deadly shooting earlier in the day — and lighting up the sky.

In one video, crowds of Jewish settlers could be heard reciting the Jewish prayer for the dead as they stared at a building in flames. And earlier, a prominent Israeli cabinet minister and settler leader had called for Israel to strike “without mercy.”

The president of the Palestinian Authority, Mahmoud Abbas, condemned what he called “the terrorist acts carried out by settlers under the protection of the occupation forces tonight.” 

“We hold the Israeli government fully responsible,” he added.

The European Union said it was “alarmed by today’s violence” in Huwara, and said “authorities on all sides must intervene now to stop this endless cycle of violence.”

As videos of the violence appeared on evening news shows, Prime Minister Benjamin Netanyahu appealed for calm and urged against violence. “I ask that when blood is boiling and the spirit is hot, don’t take the law into your hands,” Netanyahu said in a video statement.

The Israeli military said that its chief of staff, Lieutenant General Herzl Halevi, was rushing to the scene and that forces were trying to restore order.

A Palestinian official who monitors Israeli settlements in the Nablus region, Ghassan Douglas, said that settlers burned at least six houses and dozens of cars in Huwara, and reported attacks on other neighboring Palestinian villages. He estimated around 400 Jewish settlers took part in the attack.

“I have never seen such an attack,” he said.

The violence occurred shortly after the Jordanian government, which hosted talks Sunday at the Red Sea resort of Aqaba, said the sides had agreed to take steps to de-escalate tensions and would meet again next month ahead of the Muslim holy month of Ramadan.

“They reaffirmed the necessity of committing to de-escalation on the ground and to prevent further violence,” the Jordanian Foreign Ministry announced.

After nearly a year of fighting that has killed more than 200 Palestinians and more than 40 Israelis in the West Bank and Jerusalem, the Jordanian announcement marked a small sign of progress. The situation on the ground, though, immediately cast those commitments into doubt.

Prominent members of Israel’s government called for tough action against the Palestinians. Israel’s finance minister, Bezalel Smotrich, a settler leader who lives in the area and has been put in charge of much of Israel’s West Bank policy, called for “striking the cities of terror and its instigators without mercy, with tanks and helicopters.”

An Israeli ministerial committee gave initial approval to a bill that would impose the death penalty on Palestinians convicted in deadly attacks. The measure was sent to lawmakers for further debate.

There were also differing interpretations of what exactly was agreed to in Aqaba between the Palestinians and Israelis.

Jordan’s Foreign Ministry said the representatives agreed to work toward a “just and lasting peace” and had committed to preserving the status quo at Jerusalem’s contested holy site.

Tensions at the Temple Mount have often spilled over into violence and two years ago sparked an 11-day war between Israel and the Hamas militant group during Ramadan.

Officials with Israel’s government played down Sunday’s meeting. A senior official, speaking on condition of anonymity under government guidelines, said only that the sides in Jordan agreed to set up a committee to work at renewing security ties with the Palestinians. The Palestinians cut off ties last month after a deadly Israeli military raid in the West Bank.

Mr. Netanyahu’s national security adviser, Tzachi Hanegbi, who led the Israeli delegation said there were “no changes” in Israeli policies and that plans to build thousands of new settlement homes approved last week would not be affected. He said “there is no settlement freeze” and “there is no restriction on army activity.”

The Jordanian announcement had said Israel pledged not to legalize any more outposts for six months or to approve any new construction in existing settlements for four months. The Palestinians, meanwhile, said they had presented a list of grievances, including an end to Israeli settlement construction on certain lands and a halt to Israeli military raids on Palestinian towns.

Sunday’s shooting in Huwara came days after an Israeli military raid killed 10 Palestinians in the nearby city of Nablus. The shooting occurred on a major highway that serves both Palestinians and Israeli settlers. The two men who were killed were identified as brothers, ages 21 and 19, from the Jewish settlement of Har Bracha.

Mr. Hanegbi was joined by the head of Shin Bet, who attended the talks in neighboring Jordan. The head of the Palestinian intelligence services as well as advisers to Mr. Abbas also joined.

In Washington, President Biden’s national security adviser, Jake Sullivan, welcomed the meeting. “We recognize that this meeting was a starting point,” he said, adding that implementation will be critical.

It was a rare high-level meeting between the sides, illustrating the severity of the crisis and the concerns of increased violence as Ramadan approaches in late March.

In Gaza, Hamas, which seeks Israel’s destruction and which Israel and America consider a terrorist organization, criticized Sunday’s meeting and called the shooting a “natural reaction” to Israeli incursions in the West Bank. Israel withdrew from Gaza in 2005. Hamas subsequently took control of the territory, and Israel and Egypt maintain a blockade over the territory.