MOSCOW — A 9-year-old boy died of his injuries today, bringing the death toll in the crash of a Russian passenger plane that slammed into a highway in heavy fog to 45, officials said.

The RusAir flight from Moscow crashed just moments from landing at the Petrozavodsk airport.

Eight people initially survived, dragged from the burning wreckage by locals. The ministry said the boy died of his injuries early today. His mother died in the crash, but a 14-year-old sister survives.

Russia’s Deputy Prime Minister Sergei Ivanov said Tuesday that preliminary information shows the crash was caused by the jet’s pilot missing the runway in adverse weather conditions.

Aviation officials said the plane’s approach was too low, so it clipped a tree and then hit a high-power line before slamming into the ground. A traffic controller who oversaw the plane’s approach said that visibility near the airport was bad, but the pilot still decided to land.