Seven people were shot and an eighth suffered a knee injury at a teen party at WorkPlay in Birmingham Sunday night.

Birmingham police said gunfire erupted outside the event venue in the 2200 block of Fifth Avenue South as the party was preparing to end. When the shooting was over, seven were shot and an eighth suffered a dislocated knee.

Seven of the injured are in their teens and one is 20 years old. One of the injured is in custody. The party is believed to have been hosted by a high school sorority.

Initially, one of the victims was thought to have suffered a life-threatening injury, but that victim's condition was upgraded and all victims are expected to recover, said Birmingham police spokesman Sgt. Johnny Williams. Several teens were detained for questioning.

"One of the inured persons was taken into custody after he was treated. He will be held as a suspect in this shooting," a police department statement read.

Williams said the shooting happened about 10 p.m., just as the teen party was about to end for the night. A Birmingham police officer working security at the club called the South Precinct for backup to help with the big crowd and expected traffic as the party ended.

While extra officers were en route to WorkPlay, two male teens inside the venue are believed to have gotten into some type of dispute. That dispute spilled outside and that's when shots rang out from multiple locations.

Police evidence markers indicated a couple of shots were fired just outside WorkPlay's front door and there were at least 14 other shell casings in a parking lot across the street.

None of the shots were fired inside Workplay, and Williams said police don't yet know how many people fired shots.

"We don't believe most of the persons injured were actually involved,'' in the initial dispute Williams said. All of those injured were teens, and believed to be innocent bystanders.

As bad as it was, Williams acknowledged it could have been worse.

"Anytime you have gunfire in a crowd of people, that is very dangerous to all involved,'' he said.

Williams said they are questioning a couple of teens to determine their involvement. "Right now we're continuing to investigate to try to determine who is responsible for those injured and we want to get them in custody."

Police continued to investigate the scene well into Monday morning. As they did so, dozens of family members of victims gathered at Children's of Alabama where the wounded were being treated.

Walteria Davis, 16, was not at WorkPlay but said her 15-year-old cousin was shot in the buttocks. She had not yet been able to see him, but had talked with him on Facetime while he was being treated for his wound.

"It's not right,'' Walteria said of the shooting, and the spate of violence affecting teens in the city and elsewhere. "Where is it coming from? It didn't use to be this way."