He is the son of assassinated Supreme Leader Ayatollah Ali Khamenei.
President Donald Trump announced "major combat operations" against Iran on Feb. 28, with massive joint U.S.-Israel strikes attack targeting military and government sites, officials said.
Iranian state television confirmed that Ayatollah Ali Khamenei was among those killed by airstrikes in Tehran on the first day of strikes. His successor is yet to be named.
Iran is responding to the operation with missile and drone attacks targeting Israel, regional U.S. bases and multiple Gulf nations. Israel is also intensifying its long-running strike campaign against the Iran-backed Hezbollah militia in Lebanon.
(Read previous Iran live updates here.)
Watch special coverage on Nightline, "War with Iran," each night on ABC and streaming on Disney+ and Hulu.
Iranian state television said that the mourning ceremony for Iran's slain Supreme Leader Ayatollah Ali Khamenei planned for Wednesday evening had been postponed and will be held later at a time yet to be announced.
The announcement came after another wave of intense strikes targeting the capital Tehran.
-ABC News' Morgan Winsor
Defense Secretary Pete Hegseth and Gen. Dan Caine, chairman of the Joint Chiefs of Staff, are scheduled to hold a press conference at 8 a.m. ET on Wednesday, the Department of Defense said in a statement.
Iran has announced the start of three days of public mourning for slain Supreme Leader Ayatollah Ali Khamenei.
Khamenei's body will lay in Tehran's Imam Khomeini Mosque from 10 p.m. local time on Wednesday evening, where mourners will be able to pay their respects.
This signals the beginning of the funeral process for Khamenei. Prayers and public speeches will be broadcast live on state television.
-ABC News' Joe Simonetti
The Human Rights Activists News Agency (HRANA), a U.S.-based group that relies on a network of activists in Iran for its reporting, said in a statement Tuesday night that it has so far documented the deaths of 912 civilians and the injuries of 211 civilians in Iran, as a result of the ongoing U.S.-Israeli military operation.
Among those killed are at least 181 children under the age of 10, according to HRANA.
HRANA said it is reviewing 880 reports of other deaths.
"These figures reflect a devastating and escalating human toll and represent absolute minimums," the group said in the statement. "The protection of civilians is not optional. It is a binding legal obligation."
HRANA said it has also "verified credible reports of attacks on at least seven medical centers and emergency health facilities" in Iran.
ABC News cannot independently verify these numbers or information, but HRANA has been accurate in its reporting during previous periods of unrest and conflict in Iran.
-ABC News' Somayeh Malekian and Morgan Winsor
