At least four people were killed Wednesday and more than 20 others injured when two explosive devices blew up under a commuter train in a southern Russian town, near the war-torn Muslim Republic of Chechnya.
Officials in southern Russia say that more than 50 passengers were on the train, when two bombs went off on the rails under one railroad car. Rescuers soon arrived on the scene and worked to evacuate the injured and bring them to hospital.
The bombings occurred on a commuter train in the North Caucasus Mountain region that is famous for its thermal springs and spa resort towns. Police say they arrested one injured man as he tried to flee from the scene of the attack.
The blasts came just as President Vladimir Putin was to meet with regional governors in Rostov-on-Don, several hundred kilometers away. The authorities made no immediate link between the bombings and Chechen rebels who have long been fighting Russian troops in Chechnya - which is also not far from where the blasts went off.
A series of bombings linked to the separatist guerrillas has struck Russia in recent months, many of them in the southern region. At least 150 people have been killed in the different incidents. Security has been tightened around Russia ahead of a presidential election, to take place in Chechnya early next month.
The rebels reject the election as merely an attempt by Moscow to secure its grip on the separatist region.
In daily attacks in Chechnya, itself, rebel groups have often targeted pro-Moscow Chechen policemen and local officials, in addition to Russian troops.
Frequent attacks take an almost daily death toll in Chechnya - even as the Kremlin insists that the election represents a major step in demonstrating that the war in Chechnya is over.
President Vladimir Putin rose to power in 1999, largely because of his tough line against Chechnya.
The political stakes are rising again, given that elections for a new national parliament will take place in December, followed by a presidential election next March.