The raid was carried out jointly by police and NGO 'Childline' last night, a police official said, adding that two persons including the canteen's manager have been arrested in connection with the case.
The children - five from West Bengal and one from Aligarh - have been rescued and efforts are on to contact their families, he added.
According to the official, the children told the police that they were mistreated by the manager.
An FIR has been registered against the college's director, the canteen's manager and two others who supplied the children for employment.
The arrested have been identified as Pradip Kumar, canteen's manager, and Phool Kumar, who provided the children for labour.