Fazekas said most of the victims were in stable condition and receiving treatment at hospitals.
Seven people, including three women, were shot in a single incident in Gary early Sunday morning, police said.
Witnesses say some kind of argument erupted in the parking lot outside Dirtty's Jazz and Blues Club around 2:30 a.m. Sunday, just half an hour before the club closes.
The shooting happened early Sunday morning in the city of Gary near Chicago. An eighth person hurt his leg while trying to get to safety.
"One is in custody right now and the other one is going to be identified; I'm working on that right now", Detective Sgt. William Fazekas told the paper.
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The weapon can not be integrated into North Atlantic Treaty Organisation defences. The US-led coalition says it does not discuss the location of its forces.
One man is in custody, but a motive remains unknown.
Gary police have responded to this location 14 times in the past two years, and "most of those incidents were routine nonviolent events such as alarm calls", Westerfield said.
No details about ages or conditions were immediately released, officials said.
Westerfield said the shooting appears to be an isolated incident and a person of interest has been identified.
Police did not say whether anyone had died from his or her injuries.