The FSB security service said in a statement quoted by Russian agencies that the raid was part of an operation to detain "wanted persons accused of participating in illegal armed groups in the North Caucasus".
"Criminals were destroyed by return fire when they attempted to resist," the FSB said, without specifying how many suspects were killed.
Local online newspaper Fontanka.Ru reported that two alleged militants were killed and three arrested.
TV footage showed heavily-armed men in balaclavas cordoning off the multistorey apartment block on the outskirts of the northwestern city famed for its tsarist-era palaces.
Special operations against suspected Islamists are frequent in Russia's North Caucasus region but have been rare in Moscow and Saint Petersburg in recent years.
Russia has battled a simmering insurgency in the Caucasus ever since fighting two brutal separatist conflicts with Chechnya.
Many Islamists have left for Syria and there has been little violence linked to the North Caucasus spilling out of the region in recent years, with the last such attacks in the southern city of Volgograd in 2013.
Disclaimer: No Business Standard Journalist was involved in creation of this content
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
