Russia's National Anti-terrorism Committee warned on Thursday of the risk of new blasts in Vladikavkaz, the capital of the republic of North Ossetia.
At least eight people were killed and some 40 injured in a car bombing at a market on Thursday.
"The crisis center in the republic of North Ossetia-Alania is coordinating the activity of the emergency services, security forces and law enforcement forces aimed to prevent the possibility of new blasts," an Anti-terrorism Committee statement said.
A police source in the North Caucus republic said a second car could contain explosives.
According to the committee, the blast occurred at 11:22 Moscow time (07:22 GMT) at the Vladikavkaz city market.
North Ossetian investigators have already qualified the blast as a terrorist attack.
The market has seen two terrorist attacks in the past.
In November 2008, a bus was blown up by a suicide bomber at a nearby bus station, killing 12 people and injuring more than 40. In March 1999, an explosion killed over 50 people and left 300 injured.
Russian President Dmitry Medvedev urged ministers to "immediately" do their best to help the injured and begin investigating the tragedy.
Medvedev ordered his North Caucasus envoy, Alexander Khloponin, to head to Vladikavkaz immediately.
MOSCOW, September 9 (RIA Novosti)
