Israeli forces in Gaza killed top Hamas leader Yahya Sinwar, a chief architect of last year’s attack on Israel that sparked the war, the military said Thursday. Troops appeared to have run across him unknowingly in a battle, only to discover afterwards that a body in the rubble was Israel’s most wanted man.

Israeli leaders celebrated his killing as a settling of scores, just over a year after Hamas-led militants surged out of Gaza into southern Israel in an attack that stunned the country. They also presented it as a moment for Hamas to surrender and release some 100 hostages it still holds captive.

Still, Israeli Prime Minister Benjamin Netanyahu said, “Our war has not yet ended.” Besides seeking the release of hostages, Netanyahu has said Israel must keep long-term control over Gaza to ensure Hamas does not rearm — opening the possibility of continued fighting.

For Hamas, Sinwars death is a crippling blow, but it has continually proven resilient during the war. There was no immediate confirmation from Hamas of Sinwars death.

Israeli Defence Minister Yoav Gallant addressed Hamas fighters, saying it “is time to go out, release the hostages, raise your hands, surrender.”

U.S. President Joe Biden called Sinwars death a “good day for Israel, for the United States, and for the world,” comparing it to the feeling in the U.S. after the killing of al-Qaida leader Osama bin Laden. He said he would talk with Netanyahu to discuss the pathway for bringing the hostages home to their families, and for ending this war once and for all.”

Sinwar has been Hamas’s top leader inside the Gaza Strip for years, closely connected to its military wing while dramatically building up its capabilities. He was elevated to Hamass highest spot in July after his predecessor Ismail Haniyeh was killed in an apparent Israeli strike in the Iranian capital Tehran.

In the past months, Israel has eliminated a string of senior figures from Hamas and Lebanons Hezbollah with airstrikes. Israel has claimed to have killed the head of Hamas’s military wing, Mohammed Deif, in an airstrike, but the group has said he survived.

But in Sinwars case, troops found him by chance.

An Israeli military official said that Sinwar engaged in combat” with Israeli troops operating in Gazas southernmost city of Rafah, and was spotted running into a building. The army struck the building with tank fire.

The army had suspected a number of top Hamas officials including Sinwar were in the vicinity, but Sinwar was not the target of that days specific operations, said the official, speaking on condition of anonymity under military briefing rules.

Visiting the site of the killing, Israels army chief Herzi Halevi said that while the military had conducted “many special operations in this war where we had excellent information .... Here, we didn’t have that and the response was very, very strong.”

Photos circulating online showed the body of a man resembling Sinwar with a gaping head wound, dressed in a military-style vest, half buried in the rubble of a destroyed building. The security official confirmed the photos were taken by Israeli security officials at the scene. The official spoke on condition of anonymity because of the ongoing investigation.

The military said three militants were killed in the operation. Police said one of them was confirmed as Sinwar by dental records and fingerprints, and DNA tests were ongoing. Sinwar was imprisoned by Israel from the late 1980s until 2011, and during that time he underwent treatment for brain cancer – leaving Israeli authorities with extensive medical records.

Netanyahu said Israel had “settled its account” with the man behind the Oct. 7 attack. But he added, “Today evil has suffered a heavy blow, but the task before us is not yet complete.”

He said it was an “important moment in the war” to bring home the hostages and that anyone in Hamas who surrendered weapons and assisted with hostages return would be allowed to leave Gaza safely.

Israel launched its campaign in Gaza to eliminate Hamas after the militants stormed into southern Israel on Oct. 7, 2023, killing some 1,200 people, mostly civilians, and abducting around 250 others. Some 100 captives are still inside Gaza, about a third of whom are believed to be dead.

Israel’s offensive has killed over 42,000 Palestinians, according to Gaza’s Health Ministry. It does not differentiate between civilians and combatants but says women and children make up a little more than half of the fatalities.

On Thursday, an Israeli strike hit a school sheltering displaced Palestinians, killing at least 28 people, according to Gaza’s Health Ministry.

Fares Abu Hamza, head of the Gaza Health Ministry’s emergency unit in the north, said the dead included a woman and four children, correcting an earlier report of five children. He said dozens of people were wounded.

The Israeli military said it targeted a command centre run by Hamas and Islamic Jihad inside the school. It provided a list of around a dozen names of people it identified as militants who were present when the strike was called in. It was not immediately possible to verify the names.

Israel has repeatedly struck tent camps and schools sheltering displaced people in Gaza. The Israeli military says it carries out precise strikes on militants and tries to avoid harming civilians, but its strikes often kill women and children.