As rescuers continue to search for more people in the ruins, the reason for the blast, which caused the building to collapse, is not yet known, deputy chief of the local emergency ministry, Colonel Akhmet Djeirkhanov, told the RIA-Novosti news agency.
But a criminal investigation has been launched.
Local police officials quoted by the agency said the blast occurred in the building's basement, where the base's kitchen was located and where "supposedly there were gas containers."
Earlier, officials had said it was a gas explosion, but no remains of either gas containers or any explosives were so far found.
The explosion occurred at the base of a special Defence Ministry security force in Kurchaloi, some 30km southeast of the Chechen capital, Grozny.
The base houses Chechen troops serving in a special Defence Ministry security force, called Vostok.
According to an interior ministry source up to 43 people could have been in the building.
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 land mine attacks continue.