New Delhi | A 21-year-old youth was killed and his friend injured when a Delhi Police head constable allegedly opened fire after hurling casteist abuses at them during an altercation on Sunday, according to the victim's family and police sources.

The friend of the youth was hit by the bullet that passed through the victim's body, and is undergoing treatment.

The incident occurred when Pandav Kumar, a food delivery agent, and his friend Krishan were standing on a road in Jaffarpur Kalan village around 2.30 am, and the accused, Neeraj, allegedly opened fire from point-blank range following an argument with them, police said in a statement.

Police sources said Neeraj is posted with the Delhi Police Special Cell.

Pandav's family alleged that Neeraj is a head constable with the Delhi Police. The police, however, did not confirm it.

According to police, information was received at Jaffarpur Kalan police station at around 2.30 am from a hospital regarding the admission of two persons with gunshot injuries, one of whom was declared brought dead.

Preliminary inquiry revealed that the two had attended a birthday party of a two-year-old child at a friend's residence. After the celebrations, the two men were engaged in a conversation with the hosts on the road before leaving, it said.

Police said that Neeraj, who lives on the opposite side of the road, came down and got into an argument with them. During the altercation, he allegedly fired at Kumar, who was on a motorcycle, aiming at his chest from close range.

"The bullet pierced through Kumar's chest and exited his body before hitting Krishan, who was sitting pillion, in the right side of his abdomen," the statement said.

Both were immediately rushed to a nearby hospital, where Kumar was declared dead, while Krishan is undergoing treatment.

A case has been registered against the absconding accused and efforts are on to nab him, police said.

Pandav's family claimed that the firing was unprovoked and that the accused immediately fled from the spot.

The family also alleged that the accused was under the influence of alcohol. He objected to Kumar standing on the road with his friends and asked him about his caste, they claimed.

"The moment he got to know that we are from Bihar, he opened fire and fled," Pandav's mother Meena Devi told reporters.

"I want justice for my son. He was innocent and had gone to attend a birthday party. He was working hard to support the family. The accused should be given strict punishment," she said.

A relative of Pandav said he was the sole earning member of his family.

The deceased's family members and locals gathered at the Jaffarpur Kalan police station following the incident, demanding the immediate arrest of the accused and strict action against him.

Police said Neeraj is a native of Bahu Akbarpur village in Haryana's Rohtak and has been living alone for the past 15 years.

They said they are probing the sequence of events that led to the altercation.