LAS VEGAS (AP) — A 17-year-old high school student in Las Vegas was beaten to death in an alleyway around the corner from campus by 10 of his classmates between the ages of 13 and 17, a prearranged fight that authorities said broke out over a pair of headphones and a vape pen.

But police homicide Lieutenant Jason Johansson said that detectives think the victim wasn’t originally supposed to be involved in the brawl, which the students agreed would take place after classes were done for the day at Rancho High School in eastern Las Vegas.

Jonathan Lewis Jr walked to the alleyway with his friend, whose headphones and vape pen had been stolen, Johansson said.

The deadly beating on November 1 was captured on cellphone video and widely shared on social media. Johansson described the footage as “very void of humanity.”

In the video, he said, the victim is seen taking off his shirt to prepare for the fight, and then the 10 students “immediately swarm him, pull him to the ground and begin kicking, punching and stomping on him.”

Eight of the students were arrested Tuesday by Las Vegas police and the FBI on suspicion of murder. They were not immediately identified because they are under 18.

Las Vegas police said they haven’t yet been able to identify the two remaining students, who will also face murder charges. The police department released images of the teenagers, asking for help from the public to identify them.

On Wednesday afternoon, as classes ended for the day and students were leaving campus, a small memorial with flowers and eight candles sat against a fence in the alleyway where Lewis was killed.

Rancho High School principal Darlin Delgado said in a letter this week to parents that support and resources were available for students and staff members as the beating “has and will continue to impact our school community.”

Scott Coffee, a deputy public defender with 28 years of experience in Las Vegas, said it is unusual to have so many co-defendants of such young ages charged with murder in a single case. Coffee said he had not seen court documents and does not represent any of the defendants.

“When kids are involved in this kind of activity, they take the risk by being involved,” Coffee said. “But the flip side is this: Does it look like anybody intended to kill anyone?”

A family court judge on Wednesday ordered four of the students who are 16 or older to be transferred to the adult court system, the Review-Journal reported. Hearings will be held at later dates to determine if the students under 16 will be charged as adults.

Police and prosecutors will have to measure the level of culpability for each of the 10 defendants as the case moves through the court system, Coffee noted.

“Was there somebody in charge of this group? Was somebody younger just going along with the older folks?” he said, adding that although the students face similar charges at the time of their arrests, “it doesn’t mean the resolutions are necessarily going to be similar.”

After the brawl, a person in the area found the teenager badly beaten and unconscious in the alleyway and carried him back to campus, where school staff called 911, police said.

Lewis was hospitalised with severe head trauma and other injuries until his death a week later. The coroner’s office in Las Vegas ruled the beating a homicide.

The victim’s father, Jonathan Lewis Sr didn’t respond Wednesday to requests for an interview. But on a fundraising page he created to help with funeral and medical expenses, he wrote that his son was attacked while standing up for his friend.

“Our son is a kind, loving, gentle young man who has the heart of a champion and the brightest loving energy that attracts people to him with love,” the page reads.