- Gunfire erupted inside US nightclub early Sunday morning
- 'No indications this incident is terrorism related,' police tweeted
- Last year, a shooting at a gay nightclub in Orlando killed 49 people
Cincinnati Mayor John Cranley said there was no evidence of "a terrorist attack," as with last year's Pulse nightclub slaughter in Orlando, Florida that killed 49 people in the deadliest mass shooting in U.S. history.
"However to the victims, what difference does it make?" Mr Cranley said. "People were just going to have a good time and ended up getting shot."
No arrests had been made hours after the shooting took place around 1 a.m. EDT (0600 GMT) as hundreds of people partied inside Cameo Nightlife. The club has a history of gun violence, including two shootings in 2015, City Manager Harry Black said in a statement.
Authorities believe multiple gunmen were involved in the Sunday morning shooting, which grew out of "some kind of dispute" inside the bar, Police Chief Eliot Isaac said.
The disagreement may have been started earlier in the day, Black said.
"At this point it's unclear exactly what instigated the shooting," police Captain Kimberly Williams said at a televised briefing. "Just a lot of chaos when the shots went off."
Four police officers, who were providing security in the parking lot when the shots rang out, ran into the club and treated victims, the chief said. In addition to those hit by gunfire, several people sustained minor injuries attempting to flee.
The man who was killed was identified by authorities as 27-year-old O'Bryan Spikes. Two of the injured were in critical condition, a University of Cincinnati Medical Center spokeswoman said. The others hit by gunfire were in stable condition in other area hospitals, and some were treated and released.
Ohio Governor John Kasich sent his condolences and offered state help in the case.
"Saddened to learn about last night's shooting in Cincinnati," Mr Kasich said on Twitter. "Our prayers are with the victims and families of all of those involved."
Cameo Nightlife's Facebook page says it features "College Friday's" for students 18 and older and "Saturday's 21+ grown and sexy night."
The club, a large single-story structure, is a 7-mile (11 km) drive from downtown Cincinnati near the southeast corner of the city, the heart of the second largest metropolitan area in Ohio with more than 2 million residents.