It was a huge explosion heard for miles around. The ramifications might turn out to be wider still.
Terror returned to Beirut today and turned a crowded street in an instant to a scene of utter chaos and carnage.
A car bomb it seems - and it ripped through busy shops, offices and apartments.
It was Friday afternoon; the time when parents had been picking up their children from school. The death toll has risen swiftly; the injured counted by the score.
For the people of Beirut, this is a bloody throwback to the bad old days of civil war. And a terrifying glimpse of what might be to come if their nation’s rival factions are drawn into the brutal conflict engulfing neighbouring Syria.
The bomb went off in a Christian area – not far from the headquarters of the anti-Syrian, March 14th, movement.
So far the identity of neither target nor bomber is known, but already many suspect the hidden hand of the Syrian regime.
It would be wrong to jump to conclusions in a country positioned on such a knife-edge, and the Syrian information minister has condemned the blast.
However, news that senior Lebanese intelligence officer Wissam al-Hassan was killed in the blast makes it look more like a targeted assassination.
Al-Hassan was the brain behind uncovering a recent bomb plot that let to the arrest of a pro-Syrian Lebanese politician.
So even as Damascus condemns the bombing, the finger of suspicion is being pointed ever more firmly in its direction.
Lebanon is divided between those who support President Assad and those who back Syria’s rebels.
They have clashed in Lebanon’s north but in the capital a fragile truce has held. Until today.
Lebanon’s government has promised a swift investigation, but it cannot answer the key question tonight: whether a new and incendiary cycle of violence is just beginning.