BRATSK CHECKPOINT, Russia, Nov 23 (Reuters) A bomb ripped through a bus in Russia's turbulent North Caucasus region on Thursday, killing at least five people, including a schoolgirl, and injuring 13.
About 19 people were on the bus when the explosion took place, near the Bratsk police checkpoint at the internal border between North Ossetia and Kabardino-Balkaria.
Police said the bus burst into flames after the blast.
The burnt-out remains of the vehicle, its windows blown out, stood near the checkpoint as investigators collected evidence, a Reuters reporter at the scene said.
Police sources said the blast was caused by about 300 to 400 grams (0.66 lb to 0.88 lb) of explosives packed with nails and pieces of metal. Local prosecutors refused to say if they were classifying the bomb as a terrorist attack.
One of those killed was a 9-year-old girl, police sources told Reuters. Medics at the hospital where the wounded were taken said one passenger was in critical condition.
''Five people were killed,'' a spokesman for the local emergency ministry said. ''The bus had just passed a police checkpoint on the border with Kabardina-Balkaria when the blast occurred.'' He said the bus was travelling to North Ossetia's capital, Vladikavkaz, from the southern Russian city of Pyatigorsk.
Russia is preparing to vote in parliamentary elections on December 2.
North Ossetia, nestled in Russia's North Caucasus, was the scene of the Beslan school attack in 2004 when gunmen took hundreds of children hostage. More than 330 people were killed, half of them children.
That massacre deepened the mistrust between the region's Christians and their Muslim neighbours, and between the North Ossetians and Ingushetia, who fought a brief war in the 1990s over a disputed border.
A bomb on a bus in the southern Russian city of Togliatti killed eight people and injured 50 on October 31. The authorties called it a terrorist attack.
War and strife have darkened life in the North Caucasus after more than a decade of fighting between Chechen separatists and Russian forces.
Russia says a few scattered fighters remain in Chechnya and that the war is over. But low-level fighting continues.
Over the last few months attacks -- partly driven by despair at local rulers and economic grievances -- have plagued Ingushetia, neighbour of both North Ossetia and Chechnya.
REUTERS TB BST0455