The Boeing-737-500 owned by Russian flagship airline Aeroflot crashed in an unpopulated area at 3:15 a.m. (23:15 GMT) with 83 passengers and five crew on board, investigator Vladimir Markin told RIA Novosti.
Aeroflot said the passengers on Flight 821 included seven children, and "foreign citizens including nine from Azerbaijan, five from Ukraine, and one from each of France, Switzerland, Latvia, the United States, Germany, Turkey and Italy."
Markin said the plane crashed into a ravine, and that part of the trans-Siberian rail line between Perm and Yekaterinburg was damaged.
News channel Vesti-24 has shown footage of the plane wreckage strewn over a large wooded area.
An eyewitness described to the channel how the plane had caught fire while still airborne and had hurtled downwards "like a falling comet."
Aeroflot pledged in a statement to pay bereaved families up to 2 million rubles ($80,000) in compensation per victim. The airline said the plane was on lease to the Dublin-based company Pinewatch Limited.
The Perm Territory will hold a day of mourning for the crash victims on Monday, a spokesman for the regional administration told RIA Novosti.
The disaster is the worst since Pulkovo Flight 612, which crashed in eastern Ukraine on August 22, 2006 en route from the Black Sea to St. Petersburg, killing all 160 passengers and 10 crew.