The Islamic State's Caucasus Province has claimed to have carried out the shooting at UNESCO heritage site in Russia's North Caucasus region on Wednesday.
Gunmen opened fire at the Naryn-Kala fortress in Derbent, killing one person and injuring 11 people. The Naryn-Kala fortress was declared a UNESCO World Heritage site in 2003.
Isis claimed that its fighters had attacked a gathering of Russian intelligence officers, according to SITE Intelligence Group, an online watchdog that monitors jihadist activities.
A Russian body guard was killed in the shooting, as per reports.
"With the help of Allah, the warriors of the Khalifate were able to attack a group of Russian special service officers in the city of Derbent in southern Dagestan, killing one officer and injuring the others," the Isis Caucasus Province claimed.
The Islamic State declared its presence in the North Caucasus region in June this year, after an al Qaeda-affiliate terror group, Caucasian Emirate, pledged allegiance to Isis.
The Muslim-dominated area in Russia has become a major recruiting ground for the terror group, with Abu Mukhammad Kadarsky, the leader of the Islamic State's Caucasus Province, making calls to locals to join Isis.
Last month, Russian special forces had reportedly killed several Isis-linked militants in the North Caucasus region.