In response to the attacks, an anti-terrorist operation has been launched in Dagestan, as an exchange of fire is still taking place in some of the places, some of which are also on fire, RT reported.

The attacks took place in Makhachkala, the regional capital, as well as the city of Derbent. Russian authorities called the attackers members of an "international terrorist organization" but provided no further details.

While previous reports claimed that unidentified assailants opened fire on Makachkala religious buildings with automatic firearms and then fled in a vehicle, heavy fighting was reported near the Makhachkala church, according to RIA Novosti. Local media reports said about 40 people are being held hostage inside, but authorities have not confirmed this yet.

A traffic police station in the center of Makhachkala was also attacked, resulting in several victims among police officers.

Police deaths occurred in both Makhachkala and Derbent.

A 66-year-old Orthodox priest died in the attack on the Derbent church. Earlier, a local public official claimed that the attackers had slit his throat.

The Derbent synagogue was also set on fire and firefighters were called to withdraw because it is feared that the attackers are still inside and gunshots were heard near the building, RIA Novosti reports.

The attack on police officers in Derbent was recorded on video and shared on social media. In the clip, loud gunshots can be heard, and several police cars are seen parked on the street, while law enforcement officers retaliated against the attackers.

According to witnesses, shots could still be heard in the center of Derbent. Local authorities were reportedly still fighting the attackers near the Orthodox church.

Local Muslim leaders have condemned the attacks. The head of the North Caucasus Muslim Coordination Council called the attackers "brutal and hateful beasts," while the head of the Chechen Republic, Ramzan Kadyrov, called the attacks an "evil provocation" aimed at sowing discord between religions.