Thousands gather to mourn St. Petersburg victims

The bomb recovered at St. Petersburg's Ploshchad Vosstaniya metro station, a short distance from the blast site, was likely left on a timer but failed to explode because the detonation mechanism was faulty or set incorrectly, said Neil Gibson, a senior weapons analyst at Jane's.

People gather at a symbolic memorial at Technologicheskiy Institute subway station in St. Petersburg, Russia, Tuesday, April 4, 2017.

The head of Russia's Investigative Committee Alexander Bastrykin has ordered officials to look into any potential "links" between the alleged attacker and the Islamic State (IS) group. The report said Russian investigators were trying to determine Dzhalilov's travels, but they had ascertained that the device used in the subway attack bore the hallmarks of "Syrian know-how", specifically traces of burnt sugar.

Konstantin Serov, the chief administrator in the city district where the building is located, told Russian news agencies that police deactivated an explosive device at the apartment.

The detainees were accused of seeking "mostly immigrants from the republics of Central Asia to commit crimes of a terrorist nature and encourage them to get involved in the activities of terrorist organizations", the Investigative Committee said.

The suspects are from Central Asian countries and the group of six men has been active since 2015, said theInvestigative Committee of the Russian Federation in a statement. "The recent tragic events in St. Petersburg are the best confirmation of this", Putin said.

No one has claimed responsibility for Monday's subway bombing, but Russian trains and planes long have been targeted by bombings by Islamist militants. But it has also made Moscow the target of Islamist ire, with both the Islamic State (also called ISIS) and Jabhat al-Nusra, al-Qaeda's Syrian affiliate, pledging to retaliate in Russian Federation.

With St. Petersburg residents tense following the deadly subway bombing, the collapse of part of apartment building Thursday triggered fears of a new attack until city authorities explained the cause.

As the authorities probed the circumstances of the attack, they also released the identities of most of the victims of the attack, as dozens of injured remained in hospital. "The country and the entire world share our pain".

  • Salvatore Jensen