"There are 20 people killed... And 17 injured," he said in his weekly address yesterday.
"We send our solidarity to the families of those killed and injured."
The school vehicle involved in the Friday night accident was carrying no passengers because it was not working a route at the time, a source at the Integrated Security Service, or ECU-911, said.
The agency did not specify how many passengers were traveling on the bus, which belongs to an interprovincial line.
Road accidents are one of the leading causes of death in Ecuador.