A massive explosion struck Iran’s capital Sunday as the Israeli military said it was striking targets in central Tehran. It comes one day after the U.S. and Israel attacked Iran and killed Supreme Leader Ayatollah Ali Khamenei, throwing the future of the Islamic Republic into doubt and raising the risk of regional instability.

Iranian state television and the state-run IRNA news agency announced the 86-year-old’s death early Sunday. U.S. President Donald Trump had announced his death hours earlier, saying it gave Iranians their “greatest chance” to “take back” their country.

What to know:

Khamenei has no known successor: The killing of the 86-year-old supreme leader appeared certain to create a leadership vacuum, given that he had final say on all major policies during his decades in power. Iran’s chief of army staff and defense minister killed in airstrike: Iran’s chief of army staff and defense minister were killed in an airstrike targeting a meeting of the country’s defense council, Iranian state television reported Sunday.A war powers debate in Congress is intensifying: Lawmakers will plunge into a rare war powers debate next week that could require Trump to obtain congressional approval for his military actions in Iran. Both the House and Senate, where the GOP has a slim majority, had already drafted such a resolution long before the latest strikes. How we got here: The joint U.S.-Israel attack on Iran, which officials say was planned for months, followed unsuccessful negotiations about Iran’s nuclear program and warnings from Trump. Iran responded by launching missiles and drones toward Israel and targeting U.S. military installations in the region.