A staircase collapsed on Wednesday at a school in the Ural Mountains, killing at least five children and injuring several others, Russia's Emergency Situations Ministry said.

The collapse occurred at the school in the village of Belyayevka in the Orenburg region, ministry spokesman Alexander Sorokaletovskikh said.

Salvage teams have rescued six children from under debris, four of whom have been hospitalized. But Sorokaletovskikh said there could be more bodies still buried under rubble.

He said the school was undergoing repairs but remained open.

Regional prosecutors have opened a criminal probe, he said.