An explosion has ripped through a crowded commuter train near Chechnya in Russia, killing at least 35 people. The blast derailed the train - which was packed with students and workers - between the southern resort towns of Mineralnye Vody and Kislovodsk. Interior ministry officials said the blast was caused by a bomber, but the FSB internal security agency is cautious about that claim. "We believe the explosion was carried out by a woman," a spokeswoman for the agency said. A train blast in the same area left at least four people dead in September. **Powerful blast*** The explosion happened shortly before 0740 local time (0440GMT). Russia's emergencies ministry has said that it was the result of a "terrorist act", and law enforcement officials are treating the incident as terrorism and premeditated murder. The blast destroyed the train's second carriage. At least 15 people were killed at the scene, with more dying of their wounds in hospital. Local officials described pulling bodies from the train, which has been thrown onto its side. Some of the victims were hurled from the train by the force of the blast, the BBC's Sarah Rainsford in Moscow says. There are about 30 ambulances on the scene, which is littered with shattered glass. An electrical fire is hampering relief efforts, the Associated Press news agency reports. Senior officials have already left Moscow to investigate. Russia has recently been rocked by bombings and other attacks, which the government blames on Chechen fighters. No one has claimed responsibility for the train explosions. **PHOTO CAPTION*** An image from Russian RTR television channel shows a damaged carriage of a commuter train near the southern town of Kislovodsk, Dec. 5, 2003. (Reuters - Handout)