Officials said the injuries were particularly severe as the truck was carrying gravel which poured onto the passengers in the bus and then covered the roadside.
The accident yesterday afternoon was one of the deadliest road tragedies in Moscow, whose traffic-clogged roads have become ever more dangerous in recent years.
According to preliminary information, the truck hit the bus after it turned onto a main road, smashing the bus into two with the force of the crash.
More than 60 people were injured in the accident with 32 remaining in hospital overnight for treatment, the health ministry said. A dozen victims were said to be in a serious condition.