An engine fire – not a terror attack appears to have caused the crash of a Russian jet that killed all 88 people on board.

The right engine of the Boeing 737-500 apparently failed and caught fire as the plane was preparing to land in the city of Perm in the Ural Mountains on Sunday. The plane slammed into the ground on the outskirts of the industrial city of 1 million people just a few hundred yards from small wooden houses and apartment buildings. Officials said no one on the ground was killed.

Flight 821 operated by a subsidiary of national flag carrier Aerofloat, carried 82 passengers, including six children under 10 years old, and six crew members. The plane’s flight recorders have been found, and officials said it will take three to four weeks to analyze them.