ST. PETERSBURG, Russia — At least 10 people were injured Wednesday by an explosion at a supermarket in St. Petersburg, Russia’s second-largest city and the site of a deadly subway bombing this year.

The Investigative Committee, the nation’s top investigative agency, said a device containing 200 grams (7 ounces) of explosives went off at a storage area for customers’ bags. It said the device was rigged with shrapnel to cause more damage.

No one has claimed responsibility for the explosion at a branch of the Perekrestok supermarket chain in the city’s northwest Kalininsky district.

Alexander Klaus, the chief of the local branch of the Investigative Committee, said 10 people were hospitalized with injuries.

Andrey Kibitov, a spokesman for St. Petersburg’s governor, tweeted that the injured were in satisfactory condition and one had been discharged from the hospital.