A search warrant filed Monday indicates that authorities are investigating whether a dispute between street gangs triggered a fatal shooting outside a rap concert in Spring Lake Park.

One person died and several were injured as the concert let out early Sunday. The warrant, filed by the Anoka County Sheriff's Office, seeks three of the victims' phones because they might have information related to street gang affiliations or rivalries.

Cmdr. Wayne Heath said in an interview Monday that the department is "working to truly identify if the shooting was gang-related" and noted that the investigation is still in its early stages.

Family and friends of the victim, Chai Yang, 19, have asked for privacy as they grieve the loss of the St. Paul man who was fatally shot outside Dala Thai Restaurant and Event Center.

"We would like to take this time to mourn our baby brother," a sister, Pa Dao Yang, said in a message Monday.

The shooting in the northern Twin Cities suburb wounded seven people, one from Circle Pines and the others from St. Paul, all between the ages of 19 and 38. Officials said they were all expected to recover from their injuries.

An 18-and-older event, dubbed "Bigg Monster's Ugly Sweater Party," was held at Dala Thai on Saturday night, featuring $tupid Young, a Cambodian-American rapper.

Detectives also reviewed Dala Thai surveillance video that showed the crowd leaving the venue and filing into the parking lot.

"A fight breaks out in the parking lot and a suspect can [be] seen firing multiple rounds towards the crowd from the east side of the parking lot," the warrant states. "People in the parking lot then move to cover. The suspect then appears to leave the scene in a vehicle. … The video shows victims down in the parking lot of business."

Heath said authorities know at least one person fired shots, but it's difficult to determine exactly how many were fired.

The warrant said initial information "indicates the shooting may involve a dispute between two different criminal street gangs."

Shootings, especially those with multiple victims, are rare for Spring Lake Park and all of Anoka County — the fourth largest county in the state. "What makes this different is the scale," Heath said, adding that it will take time to interview dozens of witnesses and victims.

Staff writer Libor Jany contributed to this report.