The Iron Dome system was not activated
The Iron Dome system was not activatedFlash 90

The IDF is investigating why a Color Red (Tzeva Adom) rocket-warning siren in southern Israel malfunctioned Thursday, sending residents of southern Israeli communities running to their bomb shelters.

The siren sounded early afternoon Thursday, but the army said shortly afterwards that no rockets had been fired, pointing to a glitch in the system as the cause.

Precisely what caused the malfunction is still being investigated.

One theory floated by officials is that clashes across the nearby border with Egypt - where the army has been fighting jihadists for several years now - may have set off the alarm, which is triggered automatically as opposed to via manual control.

The border between Israel and Gaza has been relatively quiet since the 2014 war between the IDF and Gazan terrorists, though the quiet has occasionally been punctuated by intermittent  rocket fire from jihadist factions independent of Hamas.

Israeli security officials have now shifted most of their focus from the rockets possessed by Hamas and other terrorist groups in Gaza - which Israel has largely learned to defend against via the Code Red and Iron Dome missile defense systems - to the threat of terrorist infiltration tunnels, which Hamas and Islamic Jihad have been busily rebuilding since Operation Protective Edge, one of which was uncovered recently by IDF forces.