Sonu, whose second name is not known, was spotted trying to break into a house in West Delhi's Prashant Vihar late on Tuesday night. With him were two others. The locals at immediately called in the police.
When the cops came, the men tried to flee by scaling a wall. Nitin and Salman managed to escape, the police said. Sonu, who fell behind, opened fire at the police party.
The policemen too, opened fire in retaliation.
Sonu, injured and profusely bleeding, was taken to the hospital, where the doctors said he needed blood. Four of the policemen, including Constable Ashok who shot him and senior officer SS Rathee, became doners.
Rishi Pal, a senior officer of the local police, said the policemen told him that while firing at the suspect was a part of their duty, donating blood was a "humanitarian duty".
A search is on for the men who had accompanied Sonu.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.