The death toll from a series of brazen attacks on churches and synagogues in Russia's mainly Muslim region of Dagestan has risen to 19 after gunmen went on the rampage in co-ordinated attacks in two of the republic's most important cities.
Gunmen with automatic weapons burst into an Orthodox church and a synagogue in the ancient city of Derbent on Sunday night, setting fire to an icon at the church and killing a 66-year-old Orthodox priest, Nikolai Kotelnikov.
In the Caspian city of Makhachkala, About 125km north, attackers shot at a traffic police post and attacked a church.
Gun battles erupted around the Assumption Cathedral in Makhachkala and heavy automatic gunfire rang out late into the night.
Footage showed residents running through the city to seek cover as plumes of smoke rose above Makhachkala.
There was no immediate claim of responsibility.
Russia's investigative committee said 15 policemen and four civilians were killed.
At least five attackers were killed, some were shown by local media shot dead on a pavement.
"This is a day of tragedy for Dagestan and the whole country," said Sergei Melikov, the head of the Dagestan region, on Monday.
He said foreign forces had been involved in preparing the attack but gave no details.
"This is an attempt to cleave apart our unity."
Dagestan announced three days of mourning.
Pictures of the dead policemen were lined up on the street before red carnations in Dagestan.
The Kremlin said President Vladimir Putin, who has long accused the West of trying to stoke separatism in the Caucasus, expressed his deepest condolences to those who lost loved ones in Dagestan.
Dagestan is a mainly Muslim republic of Russia's North Caucasus, a patchwork of ethnic groups, languages and regions that live in the shadow of the Caucasus mountains between the Caspian Sea and the Black Sea.
The attack on Christian and Jewish places of worship stoked fears Russia might be facing a renewed militant Islamist threat just three months after a deadly attack in Moscow.
In the Moscow attack, 145 people were killed at the Crocus concert hall. Islamic State claimed that attack.
In October, after the war in Gaza broke out, rioters waving Palestinian flags broke down glass doors and rampaged through Makhachkala airport to look for Jewish passengers on a flight arriving from Tel Aviv.
In Israel, the foreign ministry said the synagogue in Derbent had been burned to the ground and shots had been fired at a second synagogue in Makhachkala.
The statement said it was believed there were no worshippers in the synagogue at the time.
Derbent, one of the oldest continuously inhabited cities on earth, is home to an ancient Jewish community and a UNESCO World Heritage site.
Russia's state media cited law enforcement as saying two sons of the head of central Dagestan's Sergokala district were among the attackers in Dagestan and had been detained by investigators.
June 24-26 had been declared days of mourning in Dagestan, Melikov said, with flags lowered to half-mast and all entertainment events cancelled.
The Russian empire expanded into the Caucasus in the late 18th and early 19th centuries, but an insurgency after the 1991 fall of the Soviet Union led to two wars.
In August 1999, Chechen fighter Shamil Basayev led fighters into Dagestan in a bid to aid Dagestani Wahhabist fundamentalists, triggering a major bombing campaign by the Russian military before the Second Chechen War.
