A youth, Manish, was shot dead in broad daylight at Sector 21 market on March 24 allegedly by the four accused, Gurgaon Police Commissioner Navdeep Singh Virk said.
Those arrested have been identified as Akash alias Ashu, Manish alias Goga, resident of Gurgaon, Manjeet alias Monu and Ashok alias Mantel, residents of Rohtak, Virk said.
Police were on a lookout for Akash as he and the deceased had many quarrels in the past and Manish had allegedly made attempts earlier to kill him, police said.
Manish and the accused had earlier been friends and were involved in a case of injuring an advocate in Delhi in 2011 but had been dischared as they were juveniles, police said.
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Akash had also shot dead his classmate in 2007 at Euro school premises here using his father's revolver. He was sentenced to three years imprisonment in the case, police said.
Two country made pistols and three live bullets were recovered from the possession of the accused and their car was also seized.