Police in Fresno, California, have arrested seven suspects in a mass shooting that left four dead in November, alleging gunmen targeted a backyard where they believed rival gang members were gathered.

Police in the central valley city said this week that seven gang members were responsible for the 17 November shooting at a watch party for a Sunday afternoon football game. The suspects opened fire at a party in retaliation for a recent gang-related killing, authorities said, but the victims were not gang members and not part of the group that the suspects meant to target.

All four men killed were of Hmong descent, part of the vibrant community of families who came to California as refugees after fleeing war and violence in south-east Asia. The tragedy devastated Hmong people across the globe, and families of the victims were initially outraged at law enforcement’s suggestions that their loved ones may have had ties to gangs.

Six suspects were arrested in connection with a mass shooting in Fresno in November that left four dead. Top row from left are Johnny Xiong, 25; Pao Vang, 30, and Jhovanny Delgado, 19. Bottom row from left are Billy Xiong, 25; Anthony Montes, 27, and Porge Kue, 26. Photograph: Associated Press

Police alleged Tuesday that Mongolian Boy Society gang members were behind the killing, and that two gunmen with semiautomatic weapons attacked the home because they thought it was a party of a rival Asian Crips gang. But the investigation revealed only one person watching the football game had a connection with Asian Crips,and was “not an active gang member”, said Andy Hall, Fresno’s police chief. The department has said there was no evidence suggesting the four fatal victims were gang members.

A police spokesman said there were some people who left the party who have not been identified.

The victims were Xy Lee, 23, a well-known Hmong singer; Kou Xiong, 38, a chef at a local restaurant; Phia Vang, 31, a musician who worked at a local lab; and Kalaxang Thao, 40, who worked at an Asian grocery store. Six other people were injured.

On 17 December, police arrested Billy Xiong, a 25-year-old Fresno resident, on suspicion of mail theft and located one of the guns used to kill the four men, authorities said. The mass shooting was allegedly retaliation for the killing of his brother, Randy Xiong, 16 hours earlier. Police also eventually arrested Anthony Montes, 27; Jhovanny Delgado, 19; Pao Vang, 19; Porge Kue, 26; Johnny Xiong, 25; and Ger Lee, 27.

Hall alleged the men were “self admitted” Mongolian Boy Society members and that they all planned the shooting, but police have not said who shot the men in the backyard. Lee, Montes, Kue and Billy Xiong were charged Thursday in state court with murder, conspiracy to commit murder, attempted murder and a gang charge. The other three men were charged in federal court with conspiracy to commit murder in the aid of racketeering.

Lawyers for the suspects could not immediately be reached.

“It is bittersweet,” said Bobby Bliatout, a local Hmong community leader. “We are happy that they were caught … so we can have some closure and move on.”

He said the initial suggestion by police that the killings were gang-related had overshadowed the horror of the losses: “It’s a terrible tragedy … in minority communities, we are targeted right away with the word ‘gang’ or ‘criminals’.”

Nou Xiong, a reporter for the local Hmong TV Network, who is also one of the victim’s cousins, said many in the Fresno Hmong community were surprised to learn police had made arrests: “They thought it was going to be another cold case or just disregarded as another ‘gang shooting’. That’s what they do with minority communities.”

Vong Mouanoutoua, a local councilman, said it was clear “innocent lives were taken”, adding that people shouldn’t dwell on the gang label.

“A gang member’s life is not less important than a non-gang member’s life. It’s always a loss,” he said, noting that the men arrested were all very young. “Their lives are changed forever.”

Kou Lee, the 31-year-old brother of Xy Lee, the famous singer killed in the attack, told the Guardian after the shooting that he was “distraught” about the word gang being tied to his brother, who was well known and celebrated in Fresno: “Everybody fell in love with him when he sings.”

Xy Lee’s community was other artists and musicians, said Mitch Herr, another Hmong community leader, who had lunch with the singer a week before he was killed: “Anyone that came to know him loved him, because he was always there for the community, always there for his friends … The future was so bright for him.”