JERUSALEM — A Palestinian gunman opened fire outside an eastern Jerusalem synagogue Friday night, killing six people and wounding four before police shot him, officials said. It was the deadliest attack on Israelis in years and raised the likelihood of further bloodshed.

The attack, which took place as worshippers were celebrating the Sabbath, came a day after an Israeli anti-terrorist operation killed nine persons in the West Bank. The new attack set off public celebrations in both the West Bank and Gaza Strip, where Palestinian Arabs fired guns into the air, honked car horns, and distributed sweets.

The burst of violence, which also included a rocket barrage from Gaza and retaliatory Israeli airstrikes, has posed an early challenge for Israel’s new government, whose leaders have pushed for a hard line against Palestinian violence. It also cast a cloud over a visit by Secretary Blinken to the region Sunday.

Israeli police said the attack occurred in Neve Yaakov, a Jewish area at Jerusalem. It said forces rushed to the scene and shot the gunman. “The terrorist was neutralized,” it said, using a term that typically means an attacker has been killed. There was no immediate confirmation of his condition.

Israel’s national rescue service, MADA, initially confirmed five deaths and five other people wounded, including a 70-year-old woman, a 60-year-old woman, and a teenage boy. Jerusalem’s Hadassah Hospital later said one man in his 40s had died from his wounds.

The shooting was the deadliest on Israelis since a 2008 attack killed eight people in a Jewish seminary at Jerusalem, according to Israel’s Foreign Ministry. Given the location and timing, it threatened to trigger a tough response from Israel.

The defense minister, Yoav Gallant, scheduled a meeting with his army chief and other top security officials. Overnight Thursday, Gaza terrorists fired a barrage of rockets into southern Israel, with all of them either intercepted or landing in open areas.

Israel responded with a series of airstrikes on targets in Gaza. No casualties were reported. Earlier in the day, Mr. Gallant had ordered Israel to prepare for new action in Gaza “if necessary.”

There was no immediate claim of responsibility for Friday’s shooting. In Gaza, the Hamas spokesman, Hazem Qassem, said the attack was “a revenge and natural response” to the killing of nine Palestinians at Jenin on Thursday.

At several locations across the Gaza Strip, dozens of Palestinians gathered to celebrate the Jerusalem attack, with some coming out of dessert shops with large trays of sweets to distribute. 

In downtown Gaza City, celebratory gunfire could be heard, as cars honked and calls of “God is great” wafted from mosque loudspeakers. At  Jericho, Palestinians launched fireworks and honked horns in celebration.

The attack escalated tensions that were already heightened following the deadly military action at the West Bank town of Jenin — where nine people, including at least seven militants and a 61-year-old woman, were killed. It was the deadliest single action in the West Bank in two decades. A 10th Palestinian was killed in separate fighting near Jerusalem.

Palestinians had marched earlier Friday as they buried the last of the 10 Palestinians killed a day earlier. Scuffles between Israeli forces and Palestinian protesters erupted after the funeral for a 22-year-old Palestinian north of Jerusalem and elsewhere in the West Bank, but calm prevailed in the contested capital and in the blockaded Gaza Strip for most of the day.

Signs that the situation might be calming quickly dissolved with Friday night’s shooting. Israel’s opposition leader, Yair Lapid, a former prime minister, called it “horrific and heartbreaking.” There was no immediate response from Prime Minister Netanyahu.

Mr. Blinken’s trip is now likely to be focused heavily on lowering the tensions. He is expected to discuss the underlying causes of the conflict that continue to fester, the agenda of Israel’s new government, and the Palestinian Authority’s decision to halt security coordination with Israel in retaliation for the deadly raid.

The Biden administration has been engaged with Israeli and Palestinian leaders in recent days, the White House National Security Council spokesman, John Kirby, said, underscoring the “urgent need here for all parties to de-escalate to prevent the further loss of civilian life and to work together to improve the security situation in the West Bank.”

While residents of Jerusalem and the West Bank were on edge, midday prayers at the Al-Aqsa Mosque compound, often a catalyst for clashes between Palestinians and Israeli police, passed in relative calm.

Both the Palestinian rockets and Israeli airstrikes seemed limited so as to prevent growing into a full-blown war. Israel and Hamas have fought four wars and several smaller skirmishes since the militant group seized power in Gaza from rival Palestinian forces in 2007.

Tensions have soared since Israel stepped up raids in the West Bank last spring, following a series of Palestinian attacks. Jenin, which was an important militant stronghold during the 2000-2005 intifada and has again emerged as one, has been the focus of many of the Israeli operations.

A senior diplomat in the United Arab Emirates, Anwar Gargash, asserted that “the Israeli escalation in Jenin is dangerous and disturbing and undermines international efforts to advance the priority of the peace agenda.” The UAE recognized Israel in 2020 along with Bahrain, which has remained silent on the surge in violence.

In the West Bank, Fatah announced a general strike and most shops were closed in Palestinian cities. The PA said Thursday it would halt the ties that its security forces maintain with Israel in a shared effort to contain Islamic militants. Previous threats have been short-lived, in part because of the benefits the authority enjoys from the relationship, and also due to American and Israeli pressure.

The PA has limited control over scattered enclaves in the West Bank, and almost none over militant strongholds like the Jenin camp.

Israel says its raids are meant to dismantle militant networks and thwart attacks. The Palestinians say they further entrench Israel’s presence in what the Israelis call Judea and Samaria, which Israel liberated along with Arab-controlled parts of  Jerusalem and the Gaza Strip in the 1967 Mideast war. The Palestinians covet those territories to form any eventual state.