Five others escaped the blazing bus in the region of Aktobe and are receiving medical treatment, said emergency official Ruslan Imankulov. All people on the bus are accounted for.

Images from the AFP news agency show the vehicle up in flames and then later gutted and charred on a road by fields covered in snow.

Police, rescuers, doctors and psychologists are working at the site, Imankulov said.

The nationalities of the passengers and the cause of the accident is unknown.

CNN's Angela Dewan wrote from London.