The train was travelling from Vorkuta above the Arctic Circle when nine of its 14 carriages derailed Wednesday evening in the Komi Republic, sparsely populated and with a harsh climate.
The 16-year-old girl was the latest of three bodies found under overturned carriages, the state-run RIA Novosti news agency reported. An unnamed woman told RIA Novosti that her husband, an energy worker in the far northern town of Salekhard, was among those killed.
Ten people were hospitalised with injuries.
Komi governor Vladimir Uiba filmed a video message in a wooded area, which he said has no paved roads, meaning emergency services had to use a special fire-fighting train to reach the scene.
Uiba said a 14-year-old girl travelling with her parents was in an "extremely serious" condition and had been evacuated by helicopter with an injured man.
The train was travelling to Novorossiisk on the Black Sea, a journey that takes more than five days. There were 195 passengers and 20 staff on board, Uiba said.
Russian Railways, th