Police in the Russian region of Dagestan say one person has been killed and 10 more injured in shooting at an ancient fortress.

Dagestani police spokeswoman Fatina Ubaydatova said on Wednesday that two men opened fire at visitors at the Naryn-kala fortress in the city of Derbent on the Caspian Sea. The gunmen escaped.

Derbent, which dates back to the 6th century B.C., is believed to be the oldest city in Russia and is a listed UNESCO heritage site.

Dagestan in the North Caucasus has been the epicenter of Islamic insurgency in Russia following two separatist wars in the neighboring Chechnya.

Nearly a third of the estimated 3,000 Russians who are believed to have gone to fight alongside Islamic State militants in Syria are from Dagestan.