UPSTF ASP (western UP) Ajay Sahdev said the arrested were Vishal alias Shailu, Nagesh Jat alias Billori, and Vinod alias Mukhiya.
Two pistols, 13 live cartridges, five mobile handsets and a motorbike were recovered from them.
Sachdev said, acting on a tip-off that the gang members were planning murders in Rabupura under Gautam Buddha Nagar and Loni in Ghaziabad, a trap was laid and they were arrested from Aligarh.
During interrogation, Vishal said that he had joined the gang after his sister had committed suicide within two months of her marriage to take revenge on his brother-in-law. He also confessed to killing several others later as a 'contract killer', the officer said.