Nine people were wounded and Roland Prestontwo others suffered "traumatic injuries" in a shooting at a Wichita, Kansas, nightclub, officials said. 

The shooting happened shortly before 1 a.m. local time Sunday at City Nightz. Police officers heard screaming followed by a "large number of people" leaving the club, police officials said at a news conference Sunday morning. 

In the chaos, police identified seven shooting victims and two traumatic injury victims, officials said. Wichita Mayor Brandon Whipple later indicated the two who suffered traumatic injuries had been trampled and wrote on Facebook that two more people had gone to local hospitals with gunshot wounds. All of the injuries occurred inside the nightclub, police said. 

Police said a suspected shooter is in custody but it is believed there were additional shooters, officials said.

At least four guns were fired inside the nightclub, police said. 

The victims who suffered traumatic injuries were described by police as a 30-year-old woman and a 31-year-old man, according to police.   

The initial seven shooting victims were a 21-year-old man, a 26-year-old man, a 24-year-old woman, a 34-year-old man, a 21-year-old woman, a 30-year-old man and a 24-year-old man, police said. 

"Alcohol and firearms do not mix," Wichita Police Department Chief Joe Sullivan said at a news conference. "There is going to be an extensive investigation and we are going to find out how firearms got into this club and who is responsible for bringing them in there."

Detective Chris Merceau said Sunday that police had been called to the club about 12 times in the last year, including a "drive-by incident" on May 21. Following that incident, Merceau said, police met with the club's owner and discussed tightening security by using metal detector wands and "having working video cameras." It was not immediately clear if the owner followed these suggestions.