Twelve people were killed and 22 injured when an explosion ripped through a two-storey military barracks in Russia's troubled province of Chechnya.
Investigators said that according to preliminary data, the blast that caused the building to collapse was caused by a natural gas leak, said Oleg Ugnivenko, a spokesman for the ministry's southern regional office.
Backing up that conclusion, there were no immediate claims of responsibility for any attack on the barracks. A news item on a Chechen rebel website reported on the gas explosion theory with scepticism but did not suggest outright that militants had targeted it.
The blast went off at the base of a special defence ministry security force in Kurchaloi, 16 miles south east of the Chechen capital Grozny.
Roman Shchekotin, a spokesman for the interior ministry's branch in southern Russia, said 43 servicemen were believed to have been inside the barracks at the time of the explosion.
The base houses Chechen troops serving in the security force, called Vostok.
Chechnya, a mainly Muslim southern Russian republic, has suffered almost continuous conflict between separatist rebels and Russian forces since 1994. Large-scale fighting has died down but skirmishing and almost daily guerrilla landmine attacks continue.Reuse content