Russia's anti-terrorism agency says its officers have arrested four people it says are connected with the Islamic State group and are suspected of planning attacks.

The National Anti-Terrorism Committee said in a statement Saturday the four were arrested in a raid in the southern republic of Ingushetia that also turned up three self-made explosive devices, grenades and firearms.

Ingushetia is one of the republics in Russia's restive Caucasus region, which is facing a simmering Islamic insurgency. Ingushetia was hit by spillover fighting from two separatist wars in neighboring Chechnya and experiences sporadic violence. In March, a car bomb exploded outside a mosque adhering to fundamentalist Salafi Islam in Ingushetia's principal city of Nazran.