One person has died and at least 15 people have been injured after at least two gunmen opened fire in a nightclub in Cincinnati, Ohio.
Police said there were "at least a couple of shooters".
They are reportedly on the run after the incident, which happened after 1am at the Cameo Club.
Those injured have been taken to four local hospitals, some by ambulance and some by their own conveyance.
The motive of the shooters are not yet known and nobody is in custody.
“At this point it's unclear exactly what instigated the shooting,” Captain Kimberly Williams said in a briefing. “We believe that there were at least a couple of shooters involved.”
She added: “Just a lot of chaos when the shots went off."
The University of Cincinnati Medical Center said it has received eight patients from the shooting, four of which were in a stable condition, three were seriously injured and one person was in a critical condition.
Family members of the victims arrived at the hospitals, awaiting updates from the police, as reports of the incident circulated.
Assistant Police Chief Paul Neudigate told a local news outlet that the shooting was one of the largest he had worked on in more than 20 years.
There were hundreds of people inside the nightclub and many of them fled when shots rang out, he said, but police were tracking down the witnesses in a "chaotic crime scene".
“We are in the middle of a very horrific situation that occurred at the nightclub with multiple victims,” he said.
“It’s going to be a long night for our homicide units to investigate.”
On its Facebook page, the club describes its Saturday night event as a "grown and sexy night" for people aged over 21.
Mr Neudigate also said that his department was "aware" that the club had faced "challenges" in the past.
Cincinnati Police Sergeant Eric Franz told CNN that the club hires police for extra security, with two officers at the entrance and two in the car park.
The shooting comes less than a year after a lone gunman burst into a gay nightclub in Orlando, Florida, killing 49 people.
Agencies contributed to this report.
