Four carriages of a train travelling from Moscow to St. Petersburg have derailed, killing several people, an emergencies official said on Friday.

"According to preliminary data, there are fatalities and injuries, but the numbers are not clear. Rescuers from St. Petersburg have left for the site," the source in the northwest region's department of the emergencies ministry told RIA Novosti.

He said the Nevsky Express accident, on the border between the Tver and Novgorod Regions, could have been caused by a power outage. A Moscow police source told RIA Novosti that the train driver had used the emergency brakes just before the derailment.

Russian Railways earlier said in a statement: "Today at 21:34 [Moscow time, 18:34 GMT], four carriages of passenger train No. 166 travelling from Moscow to St. Petersburg derailed."

RZD President Vladimir Yakunin is on his way to the site of the accident, near the town of Bologoye.

A source at a hospital in the Novogorod Region's Okulovskoye district told RIA Novosti that medics are preparing to receive the injured passengers.

VELIKY NOVGOROD, November 27 (RIA Novosti)