(CNN) -- Several people were stabbed Thursday night in a parking lot outside the Denver Broncos football game, police said.
At least three people were slashed in the scuffle at a parking lot near Sports Authority Field at Mile High, said Denver Police Sgt. Steve Warneke.
One of the victims was in critical condition, Warneke said.
Officers were also trying to determine if there was a fourth stabbing victim that did not wait to be transported by an ambulance, police said.
The incident occurred at about 10 p.m. MT, but it was unclear what started the altercation.
Officials with Stadium Management Company, the operator of the facility, said they are also investigating the incident.
"Stadium Management Company is aware of an incident that occurred in a parking lot adjacent to Sports Authority Field at Mile High. We are currently working with authorities to gather more information, " the company said.
This is second violent incident after a Broncos game this month.
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A 30-year-old man died after he got into a struggle with another person in a parking lot near the Kansas City Chiefs' Arrowhead Stadium on December 1. That incident happened after a game between the Chiefs and the Denver Broncos.
CNN's Chuck Johnston contributed to this story.
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