The accident has left at least 20 other people injured.
The bus driver apparently dodged a motorcycle and veered off the highway today in the city of Caninde, 115 kilometers southeast of Fortaleza beach.
Police in Caninde say emergency personnel found 21 people dead at the scene. The other 20 or so passengers were sent to a nearby hospital with severe wounds.
The bus company Viacao Princesa says the accident occurred when the driver lost control and the bus left the roadway.