The explosion used "the equivalent of 330 or 400 kilos of explosive material" or an "increased amount of pyrotechnic material," according to an FSB communique.
Prime Minister Vladimir Putin stated that "the events in Dagestan are dangerous not only for the republic and for the Caucasus, but also for all of Russia."
An anonymous interlocutor, "who spoke with a strong Caucasian accent," told the Interfax agency that the explosion was a response to military operations conducted by Russian forces in Dagestan and Chechnya.
Leaders of Islamic separatists have repeatedly threatened Moscow with reprisals following bombings in the region by Russian aviation.
A bomb attack in Buynaksk (Dagestan) on Saturday destroyed a building inhabited by Russian military personnel, causing 64 deaths.
Radio Deutsche Welle reported that an unknown person "with a North Caucasus accent" announced "three explosions in Moscow" on Monday by telephone, calling the bureau of the German radio station in Moscow. This person claimed the act was "an act of anger against the bombings of Chechen villages by Russian military forces."
Another explosion occurred in an underground passage in Moscow on August 31 near the Kremlin, causing one death. This explosion was attributed to radical Islamists who launched an offensive in Dagestan.
Various high-ranking Russian officials yesterday favored the "terrorist" narrative regarding the explosion that destroyed a residential building in a working-class district in southeast Moscow overnight from Wednesday to Thursday.
Russian Interior Minister Vladimir Rushailo suggested the disaster might have been caused by a bomb, adding that the final results of the specialists' investigation would be available soon, "in one or two days."
According to the same source, the epicenter of the explosion was located between the ground and first floors of the building where 202 people lived.
By the middle of yesterday evening, 23 bodies had been recovered from the ruins, 73 people were hospitalized, and about 50 remained on the list of missing persons.
17.09.99 Offensive: Explosion in Volgodonsk
The secret service managed to prevent several assassination attempts in Moscow. Boris Yeltsin stated that terrorism is historically doomed in Russia.
A bomb explosion in a residential building in Volgodonsk (South-East Russia) resulted in 14 deaths and 15 serious injuries, according to information from the city ambulance service cited by NTV television.
The bomb had a potential equivalent to 300 or 350 kilos of TNT, reported ORT television, relaying a report from the regional police, Alexei Polnyasky.
A truck parked near an 8-story building exploded shortly after 6 AM local time, destroying part of the facade and damaging neighboring buildings.
Volgodonsk is a city with a population of 200,000, located between Rostov-on-Don and Volgograd.
An investigation was opened under the "terrorism" article. FSB (Federal Security Service, ex-KGB) representative Alexander Zdanovich reported on NTV that a group of FSB experts had already left Moscow to go to the explosion site.
This was the fifth explosion in Russia since August 31. The three previous ones in Moscow and one in Buynaksk (Dagestan) resulted in a total of 275 deaths.
Meanwhile, Russian President Boris Yeltsin demanded the strengthening of the administrative border with the independentist republic of Chechnya (Caucasus) during a meeting with his Foreign Minister Igor Ivanov, according to an "Interfax" report.
Yeltsin then spoke about the Volgodonsk explosion, claiming that Russia possesses "all the forces and means necessary to put an end to terrorism."
Moscow attributes the explosions to Islamists. Prime Minister Vladimir Putin stated on Wednesday (i.e., Sept. 15) that the instigators were hidden in Chechnya.
The first four explosions were claimed by the mysterious Army for the Liberation of Dagestan, linked to Islamic extremists.