Three men were stabbed in a parking lot at Sports Authority Field after the Denver Broncos' game Thursday night.
Police spokesman Steve Warneke said a fourth person might have been stabbed but left the scene.
Warneke said one man was initially in critical condition but all are conscious and talking.
Police said officers have three suspects in custody and are not currently looking for other suspects. None had been formally charged as of just after midnight.
The Denver Post reports there were multiple eyewitnesses.
Police said the incident was called in at 9:55 p.m. and that officers responded to a large fight at Lot F at Sports Authority Field.
Warneke described the scene as "very chaotic" and said police didn't know what led up to the fight. He said police didn't know whether the men had attended the game.
Stadium Management Company said in an emailed statement that it is "aware of an incident that occurred in a parking lot adjacent to Sports Authority Field at Mile High" and it is working with authorities.
The Broncos lost 27-20 to the San Diego Chargers.
The stabbing Thursday is just one of several recent incidents involving football fans.
Earlier this month in Kansas City, Mo., a man died after an altercation in the Arrowhead Stadium parking lot during Kansas City's game against Denver.
In September in San Francisco, a teenage fan suffered a concussion and a broken arm and nose at Candlestick Park after police say he was attacked during the 49ers' game against Indianapolis.
The Associated Press contributed to this report.