Authorities in Russia's Caucasus Republic of North Ossetia say a female suicide bomber may have set off a deadly minibus explosion that killed at least nine people in the capital, Vladikavkaz.
The government's press service Thursday issued the preliminary results of an investigation into the blast that injured around 40 others, including a child.
There are conflicting reports on the death toll and injury count as officials continue investigating the blast.
In Moscow, Kremlin officials say President Dmitri Medvedev is following the investigation closely.
North Ossetia borders Ingushetia, the site of frequent attacks by Islamic separatists.
It also borders Georgia, the scene of fighting in August, when Georgian troops sought to retake control of the country's breakaway region of South Ossetia by force. Russian troops swept into the area as well as other parts of Georgia and withdrew only months later.
Russia is keeping about 8,000 troops in South Ossetia and Georgia's other breakaway region Abkhazia, which Moscow now considers independent countries.
In Washington, the U.S. State Department condemned the blast. A statement called it a "heinous act of terrorism." It also expressed condolences to the families of all those killed and injured.