The fact came to light after locals rescued on Thursday night two children at Rajshahi Railway Station and caught a street urchin assigned by a gang of child traffickers to abduct kids.
They handed over street urchin Rabbi, 12, who sells children to human traffickers in Dhaka for Tk 200 each, to the police.
Rescued Shamsher, 8, and Quamrul Hasan, 10, told the police that Rabbi was taking them to the capital to sell them to a woman for Tk 200 each.
The two kids are now kept under safe custody of Association for Community Development, a Rajshahi-based non-governmental organisation.
Police said Rabbi admitted that he sold another boy Mohibul, 8, missing for two and a half months, to a woman in the capital for Tk 200.
A police team took Rabbi to Dhaka yesterday to rescue Muhibul and arrest the gang members.