Three history-sheeters were arrested from Palam Vihar after a tip-off on Thursday night.
The accused were planning a robbery in the area. When the gang was intercepted by the police team, the criminals opened fire but were immediately nabbed. Police recovered four pistols, three live cartridges and an SUV from them.
They have been identified as Ajay Kumar, Ved Prakash and Devender Singh from Bahadurgarh and Jhajjar areas.
According to the police, the accused confessed that they killed one person in Hisar and injured another in Uttar Pradesh.
Meanwhile, five other persons said to be involved in robbery of electrical goods and mobile phones from industrial areas of Bilaspur, Rewari and Udyog Vihar were also arrested.
According to the police, the gang would recce the areas in the morning and plan robberies at night. The accused have been remanded in police custody.
In another incident, two bike-borne miscreants snatched the purse of one Vandana Tyagi of Sector 22 on Thursday night, the police said. A case was registered at the DLF City Phase 2 police station.