At least six people have been killed in an explosion that tore through a commuter train in southern Russia near the troubled region of Chechnya. More than 30 others were injured amid reports that the blast was caused by two bombs left on the track. Local police are said to have detained a man who tried to flee the area. Suffering from shock, he has been taken to hospital. The explosion happened near the spa town of Pyatigorsk, northwest of the border with Chechnya, where federal forces have been fighting Chechen fighters for most of the last decade. As the casualties were taken to hospital, where some of them are in a critical condition, Russian President Vladimir Putin telephoned the local governor to be briefed on exactly what happened. The Kremlin has put forward a peace plan for Chechnya and the authorities in Moscow are under pressure to curb the violence after a series of bomb attacks by Chechens this year, including one in the Russian capital. **PHOTO CAPTION*** A frame from Russian RTR television show investigators working at the site of an explosion on a commuter train near the town of Pyatigorsk in Russia's Northern Caucasus, September 3, 2002. (REUTERS/RTR)