The Egyptian army said Monday that militants killed five soldiers in the restive Sinai Peninsula, where security forces have been targeted in a spate of jihadist attacks.

“The armed forces mourn with great sadness and sorrow the five martyrs who were martyred in Sinai at the hands of disloyal fundamentalist elements, enemies of the nation and religion,” the military spokesman said in a statement released early Monday.

The statement did not elaborate on the cause of their deaths.

But military officials, speaking on condition of anonymity because they weren’t authorized to brief reporters, said the militants intercepted the men returning from monthly leave in a taxi, shooting them dead but sparing the driver.

Jihadists have killed hundreds of soldiers and policemen since 2013. Most of the attacks have taken place in the Sinai Peninsula, which borders Israel and the Palestinian Gaza Strip, but attacks have also been carried out in other areas including Cairo.

And the majority of these attacks have been carried out by ISIS.