Sirens warning of an incoming rocket attack sounded on Saturday evening in two communities in southern Israel near the Gaza Strip, in what the IDF said later was a false alarm.
Several past incidents in recent months have also been false alarms.
The ‘Code Red’ sirens went off moments apart on Saturday in Netiv Ha’asara and Yad Mordechai in the Hof Ashkelon Regional Council.
The military did not specify what triggered the alarms.
In the past, some rocket launches have been perpetrated by more extremist groups in the Gaza Strip, in defiance of Hamas which Israel holds responsible.
Earlier Saturday, Hamas said it had arrested four senior Islamic State members, including the group’s leader in the coastal enclave.
“This morning, security forces arrested Nour Issa, 27, who is a leader of the deviant thought movement and is from Bureij Camp in central Gaza, along with others,” a Hamas source said, using a phrase routinely used to refer to jihadists, including IS.
The internal security service confirmed on its Facebook page that it had made a number of arrests.
“One of the leaders of the deviant thought has been arrested along with others,” it said, without giving a name.
Issa and three others were holding a meeting in the house of one of the members in the southern Gaza city of Rafah when they were arrested. A large stash of weapons were also found, Hebrew media reports said.
Hamas has run Gaza for a decade but it has been challenged by small hardline factions, some of them inspired by IS, who advocate a stricter, Salafist interpretation of Islam.
Some have carried out sporadic rocket attacks into Israel in defiance of an informal truce agreed by Hamas.