"Shooting investigation underway at south-end nightclub. Preliminary info, 5 people shot/451 Franklin Ave, 1 fatally. MCD/CSD and support units on scene," Hartford police tweeted.
The dead victim was a 28-year-old man, the Hartford police said on Twitter.
Two of the wounded were still in surgery as of 7:30 a.m. (1230 GMT), the tweet said, while the two others were "stable."
Hartford police Lieutenant Paul Cicero told the Associated Press that police left the scene at around 7 a.m. (1200 GMT), amid a "long, complex investigation."
Further details, including information about the shooter, were not immediately available.
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