According to the sources, the abduction took place after the bus, filled with market-goers, was hijacked by Boko Haram militants in the Cameroonian town of Koza, which is located near the border with Nigeria.
The incident in Cameroon came after a series of Boko Haram attacks on the border towns of Bosso and Diffa in Niger.
The militants targeted a prison in Diffa on Monday but were successfully repelled by soldiers from Niger and Chad.
Recent weeks have seen an escalation of Boko Haram assaults outside Nigeria, something that has forced the country's government to postpone Nigeria's presidential and parliamentary elections from February 14 to March 28.
Boko Haram, whose name is loosely translated as Western education is forbidden, seeks to overthrow the current Nigerian government and replace it with a regime based on Islamic law.
More than 5,000 people have been killed by Boko Haram militants since 2009.
