Israel’s Iron Dome missile-defense system was mistakenly activated late Sunday night when automatic gunfire in Gaza inadvertently triggered a barrage of missile interceptors into the skies above southern Israel, according to the Israel Defense Forces. The false alarm was activated due to live-fire militia exercises conducted by Hamas.

The launch set off a wave of missile-warning sirens in the communities of Hof Ashkelon and Shaar HaNegev, and tanks fired at two Hamas positions in northern Gaza.

The IDF confirmed that no rockets were fired at Israel, and that the Gaza border is secure. An IDF spokesperson said an investigation is being launched to determine the technical reason why the Iron Dome and alarm systems were activated, so that mistakes would not occur again in the future.

Tensions along the Gaza border have risen in recent weeks. On Saturday, a group of four masked men entered Israel from Gaza and attacked heavy engineering vehicles being used to stop terror tunnels from reaching Israel.