Moscow - Russian security forces arrested three people, after disabling an explosive device in St. Petersburg today, while in the Rostov-on-Don region one person was injured when a bomb camouflaged in a bluff exploded.

The bombers worked in an apartment on the avenue Tovarishesky, official sources of the northern city said, in which underground a suicide bomber last Monday carried out an attack with a balance of 14 dead and more than 50 injured.

The detainees are people from Central Asia, but it is unknown whether they lived permanently in the apartment where they found the bomb or if they only had it leased.

At the same time, a custodian of the number five high school in Rostov del Don inspected an abandoned package near that school and on reviewing; it found a lantern that when turned on activated a bomb inside.

The incident occurred on Sotsialistechesky Street. The custodian lost his fingers and received wounds in the stomach, but doctors say the injuries are not deadly.

Police carried out canine and other equipment checks on the safety of schools in Rostov-on-Don.

Such incidents coincide with the realization in this capital and other regions of Russia of acts of solidarity with St. Petersburg and the victims of the recent attack.