A powerful bomb has ripped apart a commuter train in southern Russia, near Chechnya, killing at least 41 people and wounding more than 100 others.
The chief of Russia's federal security service, Nikolai Patrushev, says three women and a man carried out the attack. He says two women jumped out of the railway car hit by the blast seconds before the explosion.
A third woman, who seemed to be coordinating the activity, was seriously injured. Mr. Patrushev also reports that fragments of a man's body were discovered with hand grenades attached to the legs.
President Vladimir Putin denounced the bombing as an attempt to destabilize Russia before Sunday's parliamentary elections. He said such attempts will always fail. Interior Minister Boris Gryzlov says those responsible for the explosion will be found and punished.
U.S. State Department spokesman Adam Ereli says the United States condemns what he calls "this latest terrorist action." He said Washington extends its condolences to the victims' friends and families.
Chechen separatist leaders deny responsibility and say their supporters are guided by international principles of humanitarian law.
The bomb went off during the morning rush hour, as the train was heading for the town of Mineralnye Vody in Russia's Stavropol region, northwest of Chechyna.
Information for this report is provided by AFP and AP.