Updated

Four servicemen in the southern Russian republic of Chechnya have been killed after the armored infantry vehicle in which they were traveling hit a hidden explosive device.

The Interior Ministry said another seven troops were injured in the incident, which took place Thursday during a reconnaissance operation near the village of Yandi, some 40 kilometers (25 miles) outside the Chechen capital, Grozny.

Police gave no indication of who they believe set the bomb. An investigation is ongoing.

Chechnya was devastated by separatist conflicts in the mid-1990s and early 2000s, but has since attained a degree of stability under Kremlin-backed local strongman Ramzan Kadyrov.

An Islamist insurgency continues to claim the lives of police and security service officers in neighboring North Caucasus provinces, especially in Dagestan, which lies east of Chechnya.