Nishant Arora alias Noni, Nimit Gaba alias Ajay alias Kubba, and Sameer Ahmad alias Baba were arrested from Anand Vihar area on a tip-off, said DCP(East) Omvir Singh.
A juvenile has also been apprehended, Singh said.
Police said Nishant had rivalry with Vishal, who was allegedly killed in the shootout, in the business of gambling.
They had plans to bump off each other and on March 23, Vishal and his gang members had allegedly gone to Nishant's house and threatened him, they said.
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Vishal succumbed to injuries, they said, adding that the eyewitnesses told the police that Vishal was fired upon allegedly by Noni and his associates.
Noni has a strong network of followers comprising "budding criminals and minors", who used to pass on information on daily activities of police teams.
"He used to contact them through Facebook, WhatsApp etc to get details of police movement and movements of his rival gang members. Noni along with a few of his associates had come to Anand Vihar area for meeting some of his other associates," said Singh.
In 2013, he came to be known as Great Gambler in his locality, due to his habit of rigorous gambling and winning at it, said the officer.
He was shot at by rival gamblers in 2013 but survived. In 2016, he and another person Afsar killed one Nadeem in the area of Seelampur. He came out on bail and built his gang again.
"He used to spend money earned from gambling on parties organised by him in five-star hotels and used to invite several female models. He is also fond of bikes and purchased a Harley Davidson recently," added the officer.