A homemade bomb blast at a supermarket in the Russian city of Saint Petersburg injured 10 people Wednesday, officials said.
"According to preliminary information, an explosion of an unidentified object occurred in a store," Investigative Committee spokeswoman Svetlana Petrenko said in a statement.
The blast was caused by a "homemade explosive device with the power equivalent to 200 grammes of TNT filled with lethal fragments," she said.
"The investigation is looking at all possible causes of what happened," she said, adding that a probe for attempted murder had been launched.
"Ten people have been hospitalised, their lives are not in danger," said the head of Saint Petersburg investigative unit Alexander Klaus, Interfax news agency reported.
An AFP correspondent at the scene observed first responders and police as well as a car belonging the Federal Security Service (FSB), which investigates acts of terror.
Police said the blast occurred in a supermarket northeast of the city centre, with sources telling Russian agencies that the explosive device had been placed in a storage locker.
"About 6:30pm there was the sound of a blast. As a result, several people have been injured," the Saint Petersburg police said, giving the incident's location.
"There is no fire. All shoppers have been evacuated," an emergencies ministry representative told Interfax.
Witness Artur Yeritsyan told TASS news agency that he heard the blast and saw smoke in the shop, but that there were not a lot of customers at the time, with some victims being taken away by ambulances.
Russia's second city Saint Petersburg was the target of a metro bombing in April, which lead to fourteen deaths and dozens of people wounded.
The bombing was claimed by a group linked to Al-Qaeda which said it was a message to countries engaged in war with Muslims.