A 24-year-old hotel employee was shot dead and his friend injured when six men fired several rounds at them near Qutub Minar on Monday.
Police said they have detained one person and are likely to arrest the culprits soon as they have received vital clues in the case.
A financial dispute is being cited as the reason behind the fatal attack.
Police officers also said an initial probe suggests that the dead man, identified as Sonu, was not the person the criminals intended to eliminate.
His friend Sandeep, who has sustained a bullet injury in the abdomen and is in a serious condition, was possibly the target.
Sandeep is a property dealer in Mehrauli of south Delhi and police suspect he was involved in several monetary transactions, one of which must have turned into a dispute.
His family members are being questioned and his previous property deals being looked into in a bid to narrow down on suspects, said police.
The shooting took place at 1.40 pm while Sandeep, Sonu and their friends, most of them property dealers, were sipping tea at a tea shop near Qutub Minar.
They stayed in Lado Sarai, a couple of kilometres away from the crime spot.
“Two cars suddenly pulled over near the tea shop and four men armed with guns emerged outside. They fired in the direction of Sandeep and his friends without speaking a word. Two bullets pierced Sonu’s chest and one hit Sandeep in his abdomen,” a police officer said. In all, six men had arrived in the two cars.
Two-minute shoot-out
The attackers carried out the shooting in less than two minutes and sped in the cars before locals could gather at the spot.
Police were informed and the two injured were rushed to a hospital.
Sonu was declared brought dead while Sandeep is undergoing treatment.
Police have obtained the registration number of the two vehicles and are scanning CCTV images from the nearby areas.
They have registered a murder case and are investigating.
