Israel says Iran launched more than 180 missiles towards the country in a large-scale attack that further heightened fears of an all-out regional war.

Millions of people rushed to shelters before explosions lit up the night skies above Tel Aviv and Jerusalem. Paramedics said two were lightly injured by shrapnel.

The Israeli military said most of the missiles were intercepted with US help, but that there were a “small number of hits”. It accused Iran of a “dangerous escalation” and warned of “consequences”.

Iran’s Revolutionary Guards said the missiles hit their targets and that it had retaliated for the killings of the leaders of its allies Hezbollah and Hamas, as well as a top Iranian general.

The US said the missile attack appeared to have been “defeated and ineffective”, and that it was consulting with Israel on a response.

The UN’s secretary general condemned what he called the “broadening conflict in the Middle East”, adding: “This must stop. We absolutely need a ceasefire.”

The missile attack came hours after Israeli troops began an invasion of southern Lebanon to remove what the military said were “Hezbollah terror targets” in border villages that posed a threat to residents of northern Israel.

Israel has gone on the offensive against the Iran-backed Shia Islamist political and military organisation after almost a year of cross-border hostilities sparked by the war with Hamas in Gaza, saying it wants to ensure the safe return of residents of border areas displaced by Hezbollah rocket, drone and missile attacks.

Air raid sirens sounded all across Israel at around 19:30 local time (16:30 GMT) on Tuesday, as the Israel Defense Forces (IDF) warned missiles had been launched from Iran.

Within a few minutes in Jerusalem, loud explosions were heard in Jerusalem as missiles flew overhead and were intercepted by Israeli air defence systems.

Videos shared on social media showed streams of light as the missiles flew over Israel, and clouds of smoke as they were intercepted or detonated on impact.

Just over an hour later, the IDF announced that people were allowed to leave their protected spaces because it did “not identify any additional aerial threats from Iran”.

Later, IDF spokesman Rear Admiral Daniel Hagari said in a statement that “there were a small number of hits in the centre of Israel, and other hits in Southern Israel”.

“The majority of the incoming missiles were intercepted by Israel and a defensive coalition led by the United States.”

He added: “Iran’s attack is a severe and dangerous escalation. There will be consequences.

“Our defensive and offensive capabilities are at the highest levels of readiness. Our operational plans are ready.

“We will respond wherever, whenever, and however we choose, in accordance with the directive of the government of Israel.”

US National Security Adviser Jake Sullivan told reporters at the White House that he did “not know of any damage to aircraft or strategic military assets in Israel”.

“In short, based on what we know at this point, this attack appears to have been defeated and ineffective,” he added.

He also condemned the attack as “a significant escalation” and warned: “We have made clear that there will be consequences, severe consequences, for this attack, and we will work with Israel to make that the case.”

Iran’s Islamic Revolution Guard Corps (IRGC) put out a statement saying it had launched scores of ballistic missiles at “the heart of the occupied territories” and targeted unspecified “sensitive security and military” centres.

The attack was retaliation for “the violation of Iran’s sovereignty and the martyrdom” of Hamas political leader Ismail Haniyeh, who was killed by an explosion in Tehran in July that Iranian officials blamed on Israel, but Israeli officials did not claim. The statement described the missile barrage as having been “in line with the legitimate right of the nation to defend itself”.

It also said the attack was in response to the Israeli air strike in the southern suburbs of Beirut on Friday that killed Hezbollah leader Hassan Nasrallah and Brig-Gen Abbas Nilforoushan, the operations commander of the IRGC’s overseas arm, the Quds Force.

The IRGC warned Israel that it would “be faced with subsequent crushing blows” if it responded to the attack.

Later, Iranian state media claimed that missiles had hit the Nevatim, Hazterim and Tel Nof air bases, as well as Israeli tanks in Netzarim – a reference to an Israeli military corridor in central Gaza – and gas installations in the southern Israeli city of Ashkelon.

The attack took place about an hour after a senior White House official told reporters that the US had indications that Iran was preparing to imminently launch missiles at Iran.

Prime Minister Benjamin Netanyahu then told Israelis in a video statement: “We are in the midst of a campaign against Iran’s axis of evil.

“Together, we will stand steadfast in the trying days ahead of us. Together we will stand. Together we will fight and together we will win.”

Meanwhile, the US military’s Central Command announced that three additional squadrons of F-16 and F-15E fighter aircraft and A-10 attack aircraft were arriving in the Middle East, and that one squadron had already arrived.

Over the weekend, the Pentagon had also ordered the USS Abraham Lincoln carrier strike group to remain in the region to “deter aggression”.

In April, Iran launched more than 300 drones and missiles at Israel in retaliation for a deadly strike on the Iranian consulate in Syria that killed several top commanders.

Almost all of them were shot down by Israel, the US and other Western allies and their Arab partners, and an air base in southern Israel sustained only minor damage when it was hit.

Israel responded by launching a missile that hit an Iranian air base Western calls for restraint.

On Saturday, Iran’s Supreme Leader Ayatollah Ali Khamenei had promised that the death of his close ally Hassan Nasrallah would “not go unavenged”.

He gave no details, but said: “The fate of this region will be determined by the forces of resistance, with Hezbollah at the forefront.”

Iran has built a network of allied armed groups across the Middle East, which are all opposed to the US and Israel and sometimes refer to themselves as the “Axis of Resistance”. Besides Hezbollah, they include Hamas in the Palestinian territories, the Houthis in Yemen, and a number of Shia militias in Iraq and Syria.