In a suspected case of gang war, a 35-year-old gym owner was shot dead by two motorcycle-borne assailants in the posh Greater Kailash area of south Delhi, police said on Friday.
Four people have been arrested in this connection, they said.
"These four are suspected to have provided logistical support to the shooters. A Special Cell team is further interrogating them," a senior officer said.
The arrested accused have been identified as Nitalesh Tiwari, Vishal Verma and Akash Yadav of Uttar Pradesh's Azamgarh, and Naveen Baliyan of Haryana's Sonipat.
Two country-made pistols and eight live rounds were seized from them.
The officer said two more people were detained and questioned in connection with the case but the main shooter remained on the run.
The police also suspect the involvement of associates of jailed gangsters Lawrence Bishnoi and Hashim Baba in the murder.
Nadir Shah -- who previously had criminal cases, including extortion, robbery and attempted murder, against him -- co-owned a gym in Greater Kailash 1.
He would also lend money on very high interest rates, police sources said.
Shah owned a business in Dubai and was stated to be known to some Delhi police officials.
He is survived by his mother and two brothers. Shah's father hailed from Afghanistan and moved to Delhi several years ago.
At the time of the incident, some officials of the Delhi Police's Special Cell were present at the gym, where they had gone to meet an informer, a source said.
Shah was talking to a friend outside the gym when he was shot at around 10.44 pm, the police said.
CCTV camera footage purporting to show Shah talking to a person as an attacker walks towards him and fires a volley of bullets from close range later surfaced on social media.