Police then shot and killed the gunman, who investigators said had a “personal relationship” with an employee of the Duck Creek restaurant inside the Radisson Hotel & Conference Center attached to the casino, Pawlak said.
The person the shooter was targeting was not at the casino at the time, so the shooter instead shot at the intended target’s “colleagues or friends”, Pawlak said.
Authorities said there was no longer a threat to the community.
Two witnesses described the scene as chaos, hearing gunshots and seeing people “running for their lives”.
“I’m pretty thankful that I was able to get out of there, and we’re all safe,” Luehring said.
Adam Olig, also from Mayville, told the station the scene was chaotic.
“I saw people a lot closer. There were people running around, running for their lives,” Olig said.
“It was chaos everywhere. People were scattering in all directions. It was just crazy. Just crazy,” Luehring added.
The casino tweeted urging people to avoid the area as the investigation continues.
CNN has contacted area firefighters, police, the sheriff’s office and nearby hospitals for more information.
CNN’s Jessica Flynn, Chris Boyette and Andy Rose contributed to this report.