Russian authorities have made safe an explosive device found in a residential building in St Petersburg, the St. Petersburg news site Fontanka.ru reported on April 6.

Fire engines had reportedly turned up at the building and people living in apartments on two stairwells had been evacuated.

Police reportedly stormed an apartment on the eighth floor, which was rented by three men of Central Asian origin.  All of them were detained, according to Fontanka.ru.

The city is still reeling after a bomb ripped through the metro on Monday, killing 14 people.

Recall, a blast on the Saint Petersburg subway system killed 14 people and wounded more than 50 other people. 

The blast struck a crowded metro train near the city center at 2:20 local time on April 3 and came as Vladimir Putin was visiting the city. 

The Russian Investigative Committee on April 4 identified a 22-year-old Kyrgyz-born Uzbek man, Akbarjon Jalilov, as the leading suspect in the April 3 bombing.

Meanwhile, a homeless Russian man was injured on Thursday when a homemade device placed in a bag near a school exploded in the southern city of Rostov-on-Don, according to Tass news agency.

Citing a local police officer, Tass reported that the man discovered a bag containing a torch at about 6.30 am local time.  When he tried to switch it on, the torch exploded and tore off his hand.