The accused were identified as Rajesh Khati (22), Chuttan Lal and Sanjay Gandhi, said Mahaveer Prasad, an investigating officer of Motidungari police.
These arrests came following a complaint by a public health group near the burns ward of the hospital last evening, he said.
The accused used to hire blood donors or give their blood on an amount ranging from Rs 3500 to Rs 5000 to needy patients, he said.
A case under section 420 and 120 of the IPC was lodged against them, he said, adding, they would be produced in the court later in the day.