Officials in Florida have charged a 15-year-old boy with 11 counts of attempted murder following a mass shooting at a college homecoming party on Saturday.

Six adults and six minors were injured, all but one with gunshot wounds, in the gunfire near the Florida Agricultural + Mechanical University (Famu) campus in Tallahassee.

It was among five mass shootings over the weekend – cases in which at least four victims were wounded or killed, according to the Gun Violence Archive. The archive, a nonpartisan resource, has recorded 386 such cases in the US for the year so far.

On Monday, the Tallahassee police department posted on Facebook that detectives had arrested a suspect in the Famu shooting two days earlier. The agency identified the suspect as Anthony Rivers III, 15.

Police do not typically identify criminal suspects who are minors, though the severity of the charges facing Rivers made him an exception. He faces 11 charges of attempted second-degree murder and one of possession of a firearm by a delinquent after being arrested on Sunday, police said.

Tallahassee police chief Lawrence Revell said in a statement that the investigation into Saturday’s shooting was ongoing, and further arrests were possible.

“What should have been a weekend of celebration in our community instead became a night of fear and violence for the victims and their families,” Revell said.

“While this arrest marks a significant step forward, our work is far from over. We remain committed to holding those responsible accountable and getting answers for every family [affected] by this tragedy.”

The department earlier said three of the victims were seriously wounded, with one in critical condition in the hospital. Nine others had gunshot wounds, the agency said – and another person injured an ankle as they attempted to escape the gunfire.

The shooting took place just before 8pm on Saturday at an intersection near the university’s Bragg stadium, where a homecoming football game had just ended. Officers were on the scene quickly and carried some of those injured to safety through a mass of people, Revell said.

According to police, Rivers opened fire after an altercation between two groups of people who were known to each other. None of those struck was believed to have been an intended target, Revell said.

Revell on Sunday thanked members of the community who had come forward with cellphone video of the shooting and its aftermath, which he said was “vital to investigative efforts”.

Famu president Marva Johnson posted a video message on X on Sunday condemning the “senseless and despicable” violence of the night before.

“As a neighbor and community partner, we are providing our full assistance to the Tallahassee police department,” she said. “Our pride, our identity, and our future will not be defined by the challenges we face, but how we respond to them together.”