The two men arrested in a downtown Denver shooting that killed one person and wounded four others were members of warring groups within the Crips gang, according to federal court records.
Dashae Armstrong, who was charged Wednesday with possessing ammunition as a felon, was among the four people who were injured.
Denver Police announced Tuesday that another man, Joshua Hayward, had been arrested on suspicion of first-degree murder.
The shooting occurred Monday evening in a neighborhood of new apartment buildings, restaurants and bars near the Colorado Rockies' stadium.
Federal investigators believe the person killed and three of the people who were wounded were "all innocent bystanders and had no gang affiliation or association," according to the court records.
In a document seeking Armstrong's arrest, a U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives agent said Hayward was a Tre Tre Crip gang member and Armstrong is a Tre Deuce Crip gang member. Special Agent Ryan McKone described a trend of shootings and other violent acts between members of different "sets" within the Crips gang.
Informants and other law enforcement officers have reported internal conflict between the subgroups over control of criminal activity and as "retribution for prior acts of violence," McKone said.
Denver Fire Department officials found Armstrong with a gunshot wound to his leg a few blocks from the location of the shooting and reported that he matched witnesses' description of one of the shooting suspects. Video later showed that Armstrong was one of the shooters, according to court records.
According to the records, Armstrong asked a Denver detective who arrested him at the hospital if they had video "of a guy jumping out in a ski mask and shooting at me?" He declined to give police a statement.
The Federal Public Defender's office, which is representing Armstrong, did not immediately return a message Wednesday.
It was not clear if Hayward has an attorney. The 24-year-old remained in jail without bond on Wednesday, and an arrest affidavit in the case was sealed.
Denver Police spokesman Sonny Jackson declined to comment on the federal investigation. Denver Police are still investigating the sequence of events and a motive and ask any witnesses who have not been interviewed to contact them, he said.
Police Chief Paul Pazen said Tuesday that the shooting was an exchange of gunfire between the two arrested men, not a random incident.
Authorities have not released any information about the person killed, saying they were still trying to notify family.