At half past ten on Sunday night, sirens began wailing across southern Israel.
The IDF’s sophisticated systems had detected a salvo of incoming rockets from Gaza.
More than a dozen Tamir interceptor missiles were at once fired in response by Iron Dome batteries. Video footage shared online showed explosions illuminating the dark skies above.
For a short while, it seemed a success: there were no reports of anything landing on the Israeli side and local residents believed all incoming rockets had been intercepted.
IDF tanks had already begun firing in retaliation towards Hamas targets near the Gaza border and Israeli fighter jets were scrambled to deliver a more devastating response.
It was only a few minutes before officials realised something had gone wrong.
Sources in Gaza denied launching any rockets at all.
And as IDF missile defence experts analysed the data, they saw all the explosions in the sky had been of the interceptors self-destructing after they could not find an incoming target.
This was added to the fact that the current intelligence assessment is that Hamas does not want a major escalation at this point. A large salvo of rockets from Gaza would have been surprising.
Forty minutes after the sirens, the IDF’s admission came: a spokesman acknowledged there had been no rocket launches from Gaza.
It was machine gun fire by Hamas within Gaza that the Israeli systems had detected – and misinterpreted – as rocket launches.
The Israeli Air Force is now trying to work out exactly what went wrong.
Iron Dome uses radar to detect and track incoming rockets to help the system’s operators respond quickly.
Official results have yet to be published but defence sources say the likely reason is a malfunction in another sensor system.
It uses additional sensors too – and it is these that are thought to have mistaken distant machine gun fire for an incoming rocket.