Investigators in Russia on Monday said the death toll in the Dagestan attacks has risen to 20 people, with at least four civilians among the dead.

"According to preliminary data, 15 law enforcement officers were killed, as well as four civilians, including an Orthodox priest," Russia's Investigative Committee said about Sunday's attack, adding that five perpetrators had also been "liquidated."

Anti-terror operation over

Earlier, Russian media agencies had reported that the anti-terror operation launched after gunmen attacked Orthodox churches and a synagogue in Dagestan had concluded.

"Following the neutralization of the threats to the lives and health of citizens, it was decided to end the anti-terrorist operation in Dagestan from 0515 GMT," said the National Antiterrorism Committee, according to Russian news agencies.

On Sunday, security forces responded to attacks on a synagogue and an Orthodox church in Derbent and then a church and a police station in the state capital, Makhachkala, situated around 100 kilometers (62 miles) away.

Footage broadcast on Russian media showed the synagogue ablaze, while videos circulating on social media showed gun battles in the streets.

Days of mourning declared

Monday, Tuesday and Wednesday have been declared days of mourning in the region.

While there has been no immediate claim of responsibility, Russian state news agency TASS quoted anonymous law enforcement sources as saying, "the gunmen who carried out attacks in Makhachkala and Derbent are supporters of an international terrorist organization," without naming a specific organization.

Dagestan is a predominantly Muslim region situated east of Chechnya, where Russian authorities battled separatists in two brutal wars, first in 1994-1996 and then in 1999-2000.

The latest attack comes three months after more than 140 people were killed in an attack on a Moscow concert hall claimed by the so-called "Islamic State" group in Afghanistan, known as Islamic State Khorasan Province (ISIS-K).

ISIS-K has killed thousands in Afghanistan and Pakistan in attacks carried out since 2015. 

kb/ab (AFP, AP)