CNN  — 

A gunman fatally shot two people and seriously wounded another at a Wisconsin casino on Saturday night before he was shot and killed by police, according to Lt. Kevin Pawlak of the Brown County Sheriff’s Office.

Investigators believe the suspect had a “personal relationship” with an employee at the Duck Creek restaurant inside the Radisson Hotel & Conference Center, which is attached to the Oneida Casino near Green Bay, Wisconsin, Pawlak said.

The person the gunman was targeting wasn’t at the casino at the time, so the gunman instead shot the intended target’s “co-workers or friends,” Pawlak said.

Two witnesses described the scene as chaotic, saying they heard gunshots and saw people running for their lives.

“At first, we didn’t really know what to expect. Then once we seen the cop running in there with an AR-15, we knew that this is getting pretty serious,” witness Dylan Luehring of Mayville, Wisconsin, told CNN affiliate WLUK. “Once we heard the shots, we knew this is no joke anymore.”

“Pretty thankful we could get out of there, and all of us are safe,” Luehring said.

Adam Olig, also of Mayville, told the station the scene was chaotic.

“Seen people that were a lot closer. There were people running all over the place, running for their dear lives,” Olig said.

“It was chaos all over. People scattering in all directions. It was just crazy. Just crazy,” Luehring added.

Oneida Police asked the sheriff’s office to investigate the homicides and the shooting, and it asked the Wisconsin Division of Criminal Investigation to handle the police shooting of the suspect.

The names of the suspect, victims and officers involved will not be released Sunday, according to the Brown County Sheriff’s Department. Further details will be provided Monday.

The main casino and another facility are closed until further notice, the Oneida Nation of Wisconsin said. In a Twitter post, the Oneida Nation of Wisconsin offered its condolences and said it was reaching out to offer counseling for its employees.

“The Oneida Nation provides extremely broad security and surveillance throughout our properties and the highest level is present at our casino properties,” the nation said.

CNN’s Jessica Flynn, Kay Jones and Andy Rose contributed to this report.