Iran live updates: 7th killed service member is identified

The Department of Homeland Security has issued a critical incident alert following the U.S. strikes on Iran.

"Although a large-scale physical attack is unlikely, Iran and its proxies probably pose a persistent threat of targeted attacks in the Homeland, and will almost certainly escalate retaliatory actions--or calls to action--if reports of the Ayatollah's death are confirmed," according to the bulletin, which was obtained by ABC.

"In the short-term, we are most concerned that Iran-aligned hacktivists will conduct low-level cyber attacks against US networks, such as website defacements and distributed denial-of-service attacks," the alert added.

-ABC News' Luke Barr and Mike Levine

President Donald Trump said the bombing targeting Iran will continue throughout the week or even longer.

In a post on his social media platform announcing the death of Iranian Supreme Leader Ali Khamenei, Trump called on the military and police to "peacefully merge with the Iranian Patriots" to take back the country.

"The heavy and pinpoint bombing, however, will continue, uninterrupted throughout the week or, as long as necessary to achieve our objective of PEACE THROUGHOUT THE MIDDLE EAST AND, INDEED, THE WORLD!" Trump said in the post.

President Donald Trump has confirmed that Iranian Supreme Leader Ali Khamenei was killed in the joint U.S.-Israeli attack on Iran.

"Khamenei, one of the most evil people in History, is dead. This is not only Justice for the people of Iran, but for all Great Americans, and those people from many Countries throughout the World, that have been killed or mutilated by Khamenei and his gang of bloodthirsty THUGS," Trump said in a post on social media.

"This is the single greatest chance for the Iranian people to take back their Country. We are hearing that many of their IRGC, Military, and other Security and Police Forces, no longer want to fight, and are looking for Immunity from us," Trump added.

Despite Khamenei's death, Trump said the "heavy and pinpoint bombing" will continue, "uninterrupted throughout the week or, as long as necessary to achieve our objective."

Multiple Israeli officials tell ABC News that Israel has determined that Iran's Supreme Leader Ayatollah Ali Khamenei was killed in the joint U.S. and Israeli strikes on Tehran earlier Saturday. U.S. officials have been informed by the Israelis but have not independently confirmed the report, according to two U.S. officials.

President Donald Trump told ABC News he believes the supreme leader is dead, saying, "we believe so."

"I don't want to say anything definitively until I see things but we believe he is. And much of their leaders are gone," Trump told ABC News.

Earlier Saturday, an Iranian Foreign Ministry Spokesperson Esmaeil Baghaei denied reports that Khamenei and Iranian President Masoud Pezeshkian were killed in the strikes, saying they are "safe and sound," in an interview on ABC News Live.

The Israel Defense Forces said it believes almost the entirety of Iran's military leadership was killed Saturday, including the head of the Iranian Security Council, the defense minister and a top intelligence official.

Among the officials are Ali Shamkhani, the secretary of the Iranian Security Council; Mohammad Pakpour, commander of the Islamic Revolutionary Guard Corps; and Aziz Nasirzadeh, the defense minister of Iran.

-ABC News' Jordana Miller, Dana Savid, John Santucci, Anne Flaherty, Shannon Kingston and Luke Barr