The attackers riding on motorbikes intercepted the bus near the village of Petel kole around 1 p.m., fired at the passengers and set fire to the vehicle, said the same source, Xinhua news agency reported.
Niger's security forces flushed out the terrorists who dispersed in the surrounding areas.
The area known as the "three borders" (Niger-Mali-Burkina Faso) has in recent years become the theater of operations for terrorist groups which carry out deadly attacks on both sides of the borders, targeting the armed forces and the civilians.