The victim who has been identified as Arun Mann (25), was in a gym near Rishi Kunj Public School when three youths barged in and got into an argument with him.
"One of them pulled out a gun and shot Arun in his abdomen," said a police official.
However, when the trio was about to flee, a youth who was training in the gym threw a heavy humming equipment which hit one of the three accused on his head. As he collapsed, the other two managed to flee.
The accused, subsequently identified as Manjeet, was admitted to the hospital with a severe head injury. His condition was reported to be critical till the evening, he said.
Police are yet to record Manjeet's statement which would aid police in catching the other two accused.
According to preliminary investigation, it appeared to be a case of personal rivalry.
A case of murder has been registered at Alipur police station and the police are examining the CCTV footage obtained from the gym. Further investigation is on, the police official added.
