The Reuters news agency quoted police and locals in the populous African country as saying.
Local police spokesman Sanusi Abubakar said seven people had fled the scene after the bus caught fire. They were later taken to hospital.
The two rescuers told Reuters the bus was full of passengers. The bodies could not be identified. They said they had seen at least 30 bodies, including women and children.
Robberies, murders, kidnappings are regular occurrences in Nigeria. In Nigeria, those armed terrorists have carried out many attacks so far. The law enforcement is not strong enough to suppress them.