Hamas leader Ismail Haniyeh was assassinated in Tehran, Iran's paramilitary Revolutionary Guard said early Wednesday, and Hamas blamed Israel for the attack.
Israel has vowed to kill Haniyeh and other leaders of Hamas over the group's Oct. 7 attack on Israel that killed 1,200 people and saw some 250 others taken hostage.
An Israeli military spokesman did not immediately respond to a request for comment. Israel often doesn't when it comes to assassinations carried out by their Mossad intelligence agency.
Hamas said Haniyeh was killed "in a Zionist airstrike on his residence in Tehran after he participated in the inauguration of Iran's new president."
"Hamas declares to the great Palestinian people and the people of the Arab and Islamic nations and all the free people of the world, brother leader Ismail Ismail Haniyeh a martyr," the terse statement said.
In another statement, the group quoted Haniyeh as saying that the Palestinian cause has "costs" and "we are ready for these costs: martyrdom for the sake of Palestine, and for the sake of God Almighty, and for the sake of the dignity of this nation."
Hamas officials did not immediately respond to requests for further comment.
Haniyeh left the Gaza Strip in 2019 and had lived in exile in Qatar. The top Hamas leader in Gaza is Yehya Sinwar, who masterminded the Oct. 7 attack.
In April, an Israeli airstrike in Gaza killed three of Haniyeh's sons and four of his grandchildren.
In an interview with the Al Jazeera satellite channel at the time, Haniyeh said the killings would not pressure Hamas into softening its positions amid ongoing cease-fire negotiations with Israel.
Haniyeh was in Tehran to attend Iran's President Masoud Pezeshkian's swearing-in ceremony on Tuesday, along with other Hamas officials and officials from Hezbollah and allied groups. Iran gave no details on how Haniyeh was killed, and the Guard said the attack was under investigation.
Analysts on Iranian state television immediately began blaming Israel for the attack.
The killing of Haniyeh comes after Israel carried out a rare strike on Beirut, which it said killed Fouad Shukur, a top Hezbollah military commander. Hezbollah has not confirmed Shukur's death in the strike, which also killed at least one woman and two children and wounded dozens of people.
The strike came amid escalating hostilities with the Lebanese militant group. The U.S. also blames Shukur for planning and launching the deadly 1983 Marine bombing in the Lebanese capital.
There was no immediate reaction from the White House. The apparent assassination comes at a precarious time, as the Biden administration has tried to push Hamas and Israel to agree to at least a temporary cease-fire and hostage-release deal.
CIA Director Bill Burns was in Rome on Sunday to meet with senior Israel, Qatari and Egyptian officials in the latest round of talks. Separately, Brett McGurk, the White House Coordinator for the Middle East and North Africa, is in the region for talks with U.S. partners.
Israel is suspected of running a yearslong assassination campaign targeting Iranian nuclear scientists and others associated with its atomic program. In 2020, a top Iranian military nuclear scientist, Mohsen Fakhrizadeh, was killed by a remote-controlled machine gun while traveling in a car outside Tehran.
In Israel's war against Hamas since the October attack, more than 39,360 Palestinians have been killed and more than 90,900 wounded, according to the Gaza Health Ministry, whose count does not differentiate between civilians and combatants.
