A man was reportedly unresponsive and had to be flown to a Denver hospital after a fight with staff at a Casper bar over two weeks ago, according to court documents.

Casper detectives continue to investigate the altercation which occurred at the Gaslight Social on Oct. 29, in which 21-year-old Alvaro Proa was beaten.

According to an affidavit filed in support of search warrant Nov. 3 in Natrona County Circuit Court, a detective spoke with Proa at the Wyoming Medical Center emergency room shortly after the fight, where Proa was treated for a "significant" injury before being taken by air to a hospital in Denver.

Proa reportedly told the detective that he had a knife on his person while he was at the bar, but didn't recall brandishing the knife during the fight. He reportedly described it as a "framing knife" with a black handle.

A bartender at Gaslight Social, 41-year-old Geno Greer, told another detective that he had been bartending that night during the bar's Halloween party. He was one of nine to 11 bartenders who worked that night.

Greer said, according to court documents, that he saw one of the bar's bouncers, 27-year-old Lucas Sanchez, asking Proa to leave. Sanchez was trying to escort Proa, two other men and a woman out the back door.

Greer said he saw Proa "posture in a stance" opposing Sanchez, as if he was going to try to "punch a knock out" on Sanchez. Greer told police he left his position behind the bar and walked toward Sanchez.

Greer claimed he had seen Proa reach into his pocket and, due to the way Proa was standing, Greer believed Proa had either a knife or a gun.

Sanchez rushed Proa, Greer said, as Greer grabbed Proa's arm with both of his hands and hit Proa's arm on a game table.

"He has a knife," Greer reportedly yelled, as Sanchez and Proa were wrestling. Greer told police that he believed Proa had stabbed Sanchez.

After Greer hit Proa's arm on the game table, Proa reportedly yelled, "I dropped it." At that point, Greer said, he let go of Proa's arm and told everyone in the bar to back away.

Proa and Sanchez fell to the ground, Greer told the detective, and appeared to be wrestling. Greer, meanwhile, watched the other patrons -- he told police he wasn't sure whether any of the people in Proa's group were armed, and he wanted to keep an eye on them.

Greer said that when he looked back at Sanchez and Proa, he thought Sanchez had "choked [Proa] out" or otherwise put Proa into submission, as Proa was lying on the ground and not moving.

As Greer turned to walk back to the bar area to get a manager, he told police, he saw a knife on a game shelf. Greer photographed the knife and "guarded" it until police arrived.

Greer said Proa remained on the ground, not moving, until police arrived.

A manager at the Gaslight Social downloaded surveillance video for police to review. A black-handled "flip style" knife, wrapped in paper towels, was handed to officers by a bartender.

A police sergeant watched the surveillance video, which showed the fight between Proa and Sanchez. Swabs were taken of possible biological evidence in the area where the fight occurred.

Police have not said that any arrests have been made in the case. As it is an ongoing investigation, Sgt. Mike Ogden declined further comment.