The accused, identified as Validad Khan (40), Mukesh (26) and Mohd Yasin (57) were nabbed separately and 3.6 kg of contraband was recovered from their possession, Sanjeev Yadav, Deputy Commissioner of Police (Special Cell), said.
Mukesh was the first to be apprehended from Old Delhi Railway Station on March 17.
"He told us he was part of big interstate narcotics racket being run by Khan and he had received the heroin from Bareilly in Uttar Pradesh," Yadav said.
Yasin, who was alleged to have involved in 17 such cases, was arrested from Jama Masjid area here.
On the basis of the information received from the trio, teams were sent to Bareilly and Madhya Pradesh to nab the remaining members of the gang, the DCP added.