Tehran, Iran - The US and Israel launched an unprovoked war on Iran early on Saturday morning aimed at overthrowing the Islamic republic's government.

A US official told Al Jazeera that Washington was participating in the attack, and President Donald Trump confirmed the start of full-blown war in an eight-minute speech.

Two loud blasts were heard in Tehran on Saturday morning by AFP journalists, and two plumes of thick smoke were seen over the center and east of the Iranian capital. Explosion were also reported in other regions of the country, with the Israeli army announcing that government buildings and military installations were being targeted.

Both Israel and Iran announced the closure of their respective airspaces, as did other states in the region.

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Iran responded by launching extensive retaliatory missile attacks. Qatar, which hosts the largest US military base in the Middle East, said it had intercepted a rocket. Bahrain, the United Arab Emirates, Kuwait, and Iraq – all countries with a significant US military footprint – have also reportedly come under fire.

The major escalation came after weeks of threats of war made by President Donald Trump, even as Iran had been participating in intense talks related to its nuclear program. As recently as Friday, officials from Tehran had made guardedly optimistic noises about progress towards a negotiated settlement.

Saturday's opening salvo mirrored the events of June last year, when Israel launched unilateral and unprovoked attacks on Iran while it was engaged in negotiations with Washington.

Iranian state television confirmed Khamenei's death early Sunday, hours after President Donald Trump announced the killing of the 86-year-old cleric.

Iran declared the start of a 40-day mourning period for its long-time supreme leader, who was killed along with his daughter, son-in-law, and granddaughter.

Trump said in a Truth Social post that Iranian supreme leader Ayatollah Ali Khamenei has been killed, though there has been no confirmation from Tehran.

He added that the US bombing of Iran will continue as long as needed and that Khamenei's death gives Iranians their "greatest chance" for taking power.

"The country has been, in only one day, very much destroyed and, even, obliterated. The heavy and pinpoint bombing, however, will continue, uninterrupted throughout the week or, as long as necessary to achieve our objective," Trump wrote.

AFP journalists heard a series of blasts in Jerusalem, central Israel and Ramallah, in the occupied West Bank, on Saturday night, with a journalist in Tel Aviv reporting a large explosion.

The blasts followed sirens after the military said it had identified a new round of missiles launched from Iran.

Israeli Prime Minister Benjamin Netanyahu has claimed that there are "signs" that Iran's Supreme Leader Ayatollah Ali Khamenei had been killed in an attack on his compound as part of US-Israeli strikes.

"This morning, in a powerful surprise strike, the compound of the tyrant Ali Khamenei was destroyed in the heart of Tehran... and there are many signs that this tyrant is no longer alive," he said in a televised statement.

The joint US-Israeli operation against Iran involved the dropping of 30 bombs on Khamenei's compound, Israel's Channel 12 network reported.

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Meanwhile, the Pentagon confirmed that there have been no US casualties in either the US-Israeli attack or Iran's retaliation.

"There have been no reports of US casualties or combat-related injuries," the US Central Command said in a statement. "Damage to US installations was minimal and has not impacted operations."

The death toll from a horrific attack on an Iranian elementary school for girls, which has been attributed to Israel, has risen to 85, Tehran's judiciary said.

"The number of martyrs at the girls' school in Minab has increased to 85," the judiciary's Mizan Online website quoted the area's prosecutor's office as saying.

Iran's Revolutionary Guards have launched a new wave of missiles against US bases in the Gulf, state TV reported Saturday, in response to the Israeli and US strikes on the Islamic republic.

The Islamic Revolutionary Guard Corps "has started a new wave of missile attacks against American bases", state TV reported, citing the IRGC.

Iran's foreign minister said the country's supreme leader was alive, along with all high-ranking officials, after Israel and the United States launched strikes across the country on Saturday.

Foreign Minister Abbas Araghchi told NBC News that supreme leader Ayatollah Ali Khamenei was alive "as far as I know," in an interview from Tehran with the US outlet, adding that "all high ranking officials are alive".

Araghchi said he had been in contact with Gulf states and "explained for them that we have no intention to attack them but we are actually attacking the American bases in the act of self defense."

He added that while there was currently no communication with the US, "if Americans wants to talk to us. They know how they can contact me. We are certainly interested for de-escalation."

Israeli strikes hit a girls' school in the southern Iranian province of Hormozgan near the strategic sea route of the Strait of Hormuz, killing and wounding scores, Iranian state media said.

The latest official death toll stood at 40.

Israel's military also said it targeted multiple sites where senior Iranian officials had gathered in the capital Tehran on Saturday morning and was "assessing" the impact of the attacks.

A civilian was killed in Iranian strikes that hit Abu Dhabi on Saturday, the UAE's ministry of defence said in a statement, as Tehran launched attacks across the Gulf in retaliation for US and Israeli strikes.

The defence ministry reported "the fall of some missile debris in a residential area" of Abu Dhabi that "resulted in one civilian death of an Asian nationality".

Iraq's powerful pro-Iran group Kataeb Hezbollah warned Saturday it will start imminent attacks on US bases after air strikes hit an Iraqi military base housing the group.

"We will soon begin attacking American bases in response to their aggression," the group said in a statement.

Two fighters were killed Saturday in air strikes that hit the Jurf al-Sakher base, also known as Jurf al-Nasr, in southern Iraq.