An explosion derailed a passenger train in Russia's southern Dagestan region but caused no injuries, say reports.
The train was travelling to the capital Makhachkala from the Caspian port of Astrakhan when the blast happened at 2300 local time (1900 GMT).
The locomotive and two carriages came off the track in the Khasavyurt region.
Dagestan, which borders Chechnya, is an ethnically diverse mainly Muslim region with a history of violence by both rebel groups and criminal gangs.
Investigators are working at the site to discover the cause of the blast, said a local interior ministry official.
RIA Novosti news agency quoted a local official as saying an explosive device had been left on the rail tracks and exploded as the train passed.
Local transport police told Itar-Tass news agency that a gunman opened fire on the car of FSB security service officials as they headed to the blast site.
One officer was injured and taken to a nearby hospital, the agency added.