MOSCOW, Russia (CNN) -- A jet carrying 88 people crashed early Sunday morning in western Russia, killing everyone on board, an airline spokesman said.

Several foreigners were on the flight, including passport-holders from Abkhazia, Germany, France and Ukraine, said Lev Koshlyakov, spokesman for flight operator Aeroflot Nord.

Authorities are trying to confirm the presence of an American on board, Koshlyakov said.

The Boeing 737 was en route to Perm from Moscow when the pilots lost communication with air traffic control just before landing about 3:10 a.m. (2110 GMT), Koshlyakov said. He described the weather at the time as "mediocre."

Eighty-two passengers -- including seven children -- were on board, in addition to six crew members.

The cause of the crash was not immediately known and is under investigation, Koshlyakov said. Rescue teams were on the scene.