One person is dead and four others wounded in a shooting in downtown Denver near Coors Field, police said. There was no suspect in custody and no known motive.
Denver police tweeted four people were transported to area hospitals for treatment.
The shooting occurred in a neighborhood of new apartment buildings, restaurants and bars near the Colorado Rockies' stadium just as the evening rush hour was getting underway.
Police spokesman Doug Schepman said investigators did not know whether more than one shooter was involved and had no descriptions of any suspects.
A witness told The Denver Post he saw a man holding a handgun in both hands fire into a group of indigent people, and someone in the group fired back.
"Oh my God, oh my God," Hisam Derani said. "I saw him approach the crowd."
Derani said he was returning home from work when he heard about six gunshots. He said he saw one or two shots fired before he ducked.
He said a gunman got into a car, slammed the door and drove away.
Derani says police interviewed him and later asked him if a man they had detained as a potential suspect was the shooter, but Derani said he was not.
Schepman said investigators did not yet know what led to the shooting.
"It's too early in the investigation right now to be able to say exactly what happened here and why," he said. Investigators were interviewing witnesses and looking for video.
A witness told CBS Denver he saw two men talking before one man then shot the other in the head and continued to shoot.
The area surrounding the shooting was cordoned off to traffic and residents.