DAGESTAN, RUSSIA - Gunmen opened fire in two cities in Russia’s north Caucasus region of Dagestan, targeting a synagogue, two Orthodox churches and a police post and killing at least 19 police officers and a priest, Russian media reported.

“This is a day of tragedy day for Dagestan and the whole country,” Sergei Melikov, governor of the Dagestan region, said in a video published early on Monday on the Telegram messaging app.

In the city of Derbent, gunmen attacked a synagogue, home to a Jewish community in the predominantly Muslim region. Russia’s state media Tass said the attackers also shot at two nearby Orthodox churches, killing a police officer and a priest.

Footage published on social media from Derbent showed a group of gunmen engaged in heavy fire with police. Officials said the Derbent synagogue was set on fire and a clip from the scene appeared to show flames coming out of the building, which is listed as a Unesco heritage site.

In a separate shooting which occurred simultaneously, a group opened fire on police in Makhachkala, the capital of Dagestan, located about 75 miles north along the Caspian Sea coast. According to local authorities, at least one police officer was killed and six others injured.

There was no immediate claim of responsibility for the attacks in the volatile region. “We understand who is behind the organisation of the terrorist attacks and what goal they pursued,” Melikov said, without disclosing further details.

Russia’s state media cited law enforcement as saying that among the attackers had been two sons of the head of central Dagestan’s Sergokala district, who it said had been detained by investigators.

Melikov said that among the dead, in addition to the police officers, were several civilians, including an Orthodox priest who worked in Derbent for more than 40 years.

Six of the gunmen were shot and killed as the incidents unfolded, Melikov said, however a Russian state news agency, citing the National Anti-Terrorist Committee, put the number at five.

It was not possible to independently verify the reports on how many people or gunmen were killed in the attacks.

Russia’s investigative committee classified the shooting as a terrorist attack and has opened an investigation.

June 24-26 have been declared days of mourning in Dagestan, Melikov said, with flags lowered to half-staff and all entertainment events cancelled.

The restive region was in the 2000s hit by an Islamist insurgency spilling over from neighbouring Chechnya, with Russian security forces moving aggressively to combat extremists in the region.

In recent years, attacks had become rarer, with Russia’s Federal Security Service (FSB) saying it in 2017 that it had defeated the insurgency in the region.

But Russia has experienced a series of Islamist terrorist attacks recently, prompting questions about whether its extensive security agencies have been distracted by the invasion of Ukraine and the internal crackdown on anti-war dissent.

In March, the Afghan branch of Islamic State, known as Islamic State Khorasan Province, claimed responsibility for the mass shooting at a Moscow concert hall, the deadliest terror attack in years, which left 139 people dead.

Last week, Russian special forces freed two guards and killed six men linked to IS who had taken them hostage at a detention centre in the southern city of Rostov.

Dagestan has also experienced a series of antisemitic incidents. Most notably, last year a mob stormed the airport in Makhachkala, searching for Jewish passengers arriving from Israel.