The Israeli airstrike in the southern suburbs of Beirut came as the Lebanese caretaker government was having an emergency meeting to discuss the previous two days of pager and radio explosions.
It caused yet more shock in a nation which considers itself battle-hardened after years of strife, disaster and wars.
But Lebanon has been truly rocked to its core by the string of attacks over the past few days.
"These are war crimes," one Lebanese minister told us.
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The Israeli military said it had targeted and killed a senior Hezbollah military commander. They named him as Ibrahim Aqil - a man with a $7m US bounty on his head.
He's been on the US most wanted list for more than forty years after being accused of being involved in the bombing of the US embassy and US marine barracks in 1983 which killed hundreds.
But the Hezbollah stronghold of Dahieh is a heavily populated crowded residential area and packed with shops, markets, and high-rise apartments.
The strike appeared to have flattened an entire block, flipping cars and leaving other vehicles covered in a heavy blanket of thick dust and rubble.
Several people could be seen in video footage filmed by neighbours, trapped under piles of rubble.
The Lebanese health authority keeps on updating the number of people killed in the strike, with the latest figures reaching 14.
There are more than 60 injured, with some of those believed to be in critical condition. Children are said to be among the dead, missing and injured.
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'Our actions speak for themselves'
The Israeli military immediately claimed success - saying that, along with Aqil, the strike had wiped out about 10 of his elite Radwan Force.
According to an IDF spokesman, who did not provide any evidence, Aqil's team had been planning an attack into northern Israel similar to the Hamas attack on 7 October.
The Israeli Prime Minister Benjamin Netanyahu issued a very short statement on X, saying: "Our goals are clear and our actions speak for themselves."
Both the prime minister and defence minister have vowed to restore security to the north of Israel so the 60,000 residents who have fled the cross-border attacks can return to their homes.
An estimated 120,000 Lebanese have also been forced out of their homes along the border.
The airstrike in the capital is the second in Beirut in two months - both, according to the IDF, targeted at senior Hezbollah commanders.
According to sources being quoted in Lebanese media, the Hezbollah group of senior leaders was meeting in an underground basement of a large housing block when the missile penetrated.
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'Things are escalating by the minute'
It is unlikely to be seen as a justifiable precision attack - or a "targeted strike", as described by the Israeli military - if the Lebanese government ministers' reactions are anything to go by.
We spoke to several as they arrived for their emergency cabinet meeting in the hour before the attack.
They were already incensed by the back-to-back coordinated booby trap explosions of communication devices across the country. Israel has yet to confirm or deny its involvement in the blasts.
Speaking about the pager and radio explosions across Lebanon earlier this week, the country's environment minister and head of its disaster management committee Nasser Yassin said: "It's genocidal, it's indiscriminate and a violation of international humanitarian law and every other law.
"We have an insane leadership on the southern end of our borders who don't want to be indicted by the International Court of Justice."
The information minister Ziad Makary called the explosions of communication devices "a new crime... it's a war crime and not something that would pass easily trying to kill three thousand or four thousand civilians as we see them".
And Amin Salam, the economy minister, warned: "Things are escalating by the minute.
"There's more tension, more provocation. We have been doing our best to get to a peaceful solution but the escalation is unprecedented.
"It's an act of terror, regardless of who was targeted."
Most intense border fighting in nearly a year
The airstrike in Beirut came after a marked increase in cross-border exchanges - the most intense in nearly a year.
The Israeli military said Hezbollah had spent the early part of the day firing nearly 200 rockets across the border into Israel.
Many of them were intercepted by the Iron Dome defence system.
This followed the Israeli bombing of more than 50 targets in the south of Lebanon overnight - which the IDF said hit launchers and weapons stores.
The Israeli military is suffering losses too - there were two funerals today for Israeli soldiers killed on their northern border - but it's Hezbollah which seems to be paying a far heavier price right now.
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Hezbollah unilaterally entered this latest war on 8 October, much to the frustration of Lebanon's caretaker government, and a day after the Hamas attack on southern Israel.
Hezbollah have repeatedly said their actions are in support of Gaza and have continued to insist they will only stop once there's a ceasefire.
But right now, the fighting group allied to Iran - and designated a terror group by the US and UK - appears to be very much on the backfoot after three attacks in four days.
Meanwhile, Israel is ploughing on despite the cries of indignation and condemnation from the international community.
Additional reporting from Beirut with camera Jake Britton, specialist producer Chris Cunningham and Lebanon producers Jihad Jineid and Sami Zein.