Explosions and interception attempts marked Wednesday in Israel and a host of Gulf nations as Iran swore vengeance for the killing of top security official Ali Larijani in an overnight Israeli strike.

Experts said Larijani's death would make a diplomatic solution to the war more difficult and longer to reach, as incoming Iranian leaders might be "harder-edged" than their predecessors.

A barrage of Iranian missiles struck near Israel's capital and commercial hub Tel Aviv, killing two people, Israel's emergency service said. Explosions were heard in the United Arab Emirates and Qatar and interceptions were reported from Saudi Arabia as Iranian rockets and drones headed for targets including the United States' bases in the region.

In Lebanon, an Israeli airstrike hit an apartment building in central Beirut, completely flattening it as day broke. Two earlier strikes on residential apartments in other central Beirut neighborhoods killed at least six people and wounded 24 others, the Lebanese Health Ministry said.

The US-Israeli war against Iran has killed at least 1,300 people so far in Iran, more than 900 in Lebanon and 14 in Israel, according to officials in the respective countries. The US military said 13 US service members had died and about 200 injured.

According to Iran's Fars and Tasnim news agencies, funerals for Larijani and another senior figure killed by Israel — Gholamreza Soleimani, the head of the Basij paramilitary force — will start at 10:30 GMT in Tehran.

Meanwhile, Israel's defense minister said on Wednesday that the Israeli military had killed Iranian Intelligence Minister Esmail Khatib as well. Israel Katz announced Khatib's killing and said that "significant surprises are expected throughout this day on all the fronts," without elaborating.

Tehran said the killing of officials would not hinder its operations. Foreign Minister Abbas Araqchi said the United States and Israel failed to understand that the Islamic republic was a robust political system that did not depend on any single individual.

Larijani, 68, was the most prominent figure of the Islamic republic to be killed in Israeli and US attacks on Iran since Feb 28, when supreme leader Ayatollah Ali Khamenei was assassinated, igniting a war across the Middle East. Larijani had reportedly been seen walking openly with crowds at a pro-government rally last week in Tehran.

"Iran's response to the assassination of the secretary of the Supreme National Security Council will be decisive and unforgiving," Iranian army chief Amir Hatami said in a statement.

Turkish Foreign Minister Hakan Fidan also lashed out at Israel, condemning its "political assassinations" of Tehran's leaders as "illegal activities in violation of the normal laws of war".

But Israel vowed also to target the new supreme leader, Mojtaba Khamenei, who has not appeared in public since he succeeded his father.

Diplomatic solutions 'more remote'

Sultan Barakat, a senior professor of public policy at Qatar's Hamad bin Khalifa University, said Larijani's death "will strengthen the line of the hard-liners" within the Iranian government to start with, and diplomatic solutions will remain "slightly more remote" for the moment.

Larijani was able to speak to both sides of the political aisle, which made him "very important" for maintaining a "balance of power" in Iran, Barakat added.

Marwan Bishara, Al Jazeera's senior political analyst, said Israel's continuous targeting of high-profile Iranian leaders was not a normal practice in warfare.

Israel is "turning this (war) into an industry of assassinations, which is not the norm in wars," he said. "In wars, you don't start by killing political leaders, including elected leaders. That program of assassination is gangster; it's terrorism; it's not the norm of war."

Meanwhile, a senior Emirati official said on Tuesday that the UAE may join a US-led effort to protect shipping in the Strait of Hormuz, after largely shut it, raising fears of a global energy crisis.

Anwar Gargash, the diplomatic adviser to the UAE president, said talks were ongoing and no formal plan had been agreed, but that "big countries" in Asia, the Middle East and Europe bore responsibility for ensuring the flow of trade and energy.

"This is something that is in the interest of everybody," he told an online event hosted by the US think tank the Council on Foreign Relations. "Everybody has a responsibility."

The UAE has faced more Iranian attacks than any other country in the region, including Israel. Tehran has claimed that Emirati territory was used to launch an attack against Iran, an accusation that the oil-rich Gulf state has denied.