Washington DC: A gunman opened fire inside an Illinois bowling alley, killing three people and injuring three others Saturday night in what authorities believe was a random attack.

Rockford city police urged people on Twitter to stay away from the area near the Don Carter Lanes bowling alley, as it was an "active situation" and officers were clearing the site.

"It's still an ongoing investigation. We do have three individuals that are confirmed deceased," police chief Dan O'Shea said in a press conference outside the building.

He said three other people had been injured from the gunfire and were being treated at local hospitals.

One person of interest was in custody and there was no longer a threat to the community, the chief said. No motive was immediately known and no identities have been released.

Shootings are a frequent occurrence in the United States, but despite the scale of the gun violence efforts to address it legislatively have long been deadlocked at the federal level.

This has been the most violent year in Rockford's history, as the city of about 150,000 has recorded 35 murders in 2020.