The bus was heading for neighbouring Ivory Coast, she added.
The accident was one of the most serious to have occurred in recent years in the west African country.
"The two vehicles caught fire in the collision," Compaore said.
"The scene is gruesome. The bus is completely 'askew', there are bodies on the road, some are in the wreckage, there are charred bodies which we are still removing. It's really horrible."
So far 20 injured, six of them seriously hurt, have been taken from the bus but "it is a very provisional figure because the fire services are still working," she said.
"Only 10 of the bodies can be identified; all the other victims are burnt beyond recognition."