At least 19 people were killed after armed men attacked a synagogue, churches and police post in Russia’s Dagestan region on Sunday.
The region has announced three days of mourning starting Monday.
Here’s what we know about the attacks in Dagestan and why they have caused concern in Russia.
Shortly before 6pm local time (15:00 GMT) on Sunday, some attackers used automatic weapons to attack a synagogue and an Orthodox church in Derbent city, Dagestan’s interior ministry said.
Derbent is home to an ancient Jewish community in the mainly Muslim region.
The interior ministry said gunmen simultaneously attacked a traffic police post in Dagestan’s capital Makhachkala, about 125 km (75 miles) north of Derbent.
The attackers and law enforcement officials exchanged gunfire. Heavy shooting was reported at the Russian Orthodox Assumption Cathedral in Makhachkala.
Russia’s National Antiterrorism Committee said a counterterrorism operation was launched in Dagestan at 8:15am (05:15 GMT) on Monday. It was declared over soon after. During such operations, authorities can restrict people’s movement and communications.
