The incident occurred last mid-night when, when around seven persons refused to pay their bill at a bar in Haridevpur area in south Kolkata, a police officer said.
The bar authorities informed police to sort out the matter but the cops were outnumbered by the miscreants as they called up their associates, he said.
"The gang was carrying weapons, including firearms and bombs and fired around 30 to 35 rounds and hurled bombs. During the firing three locals were hit and taken to the M R Bangur Hospital where one was declared brought dead. The other two are being treated," the officer said.
"We are checking the CCTV footages of the bar and trying to track the persons involved. We suspect that these persons are from the nearby Basdroni or Sonarpur fringe areas," he added.