LAS VEGAS (AP) — Prosecutors in Las Vegas have formally charged four high school students as adults with murder in the deadly beating of their schoolmate, a fight that was captured on cellphone video and has been widely shared across social media.

The two 16-year-olds and two 17-year-olds are charged with second-degree murder and conspiracy to commit battery.

After court, District Attorney Steve Wolfson said his office chose not to bring a first-degree murder charge against the teens because, he said, the evidence shows that the beating was not a premeditated act.

The four teens will remain held without bail, but a judge on Tuesday granted a joint request from prosecutors and defense attorneys to transfer them from the county jail to the juvenile detention center, citing the teens’ safety.

At least eight students between the ages of 13 and 17 have so far been arrested in connection with the Nov. 1 brawl that left 17-year-old Jonathan Lewis Jr. dead. The other students are awaiting separate hearings because they are all under the age of 16.

The Associated Press is not naming the students because they are juveniles.

Wolfson told reporters outside the courtroom that one more student has been arrested. Las Vegas police have said they believed 10 students took part in the beating and that they were working to identify and locate them.

A spokesperson for the police department said Tuesday he didn’t immediately have details about a ninth arrest in the case.

Authorities have said that the students at Rancho High School in east Las Vegas had agreed to meet off-campus after school to fight over items stolen the victim’s friend said were stolen, including a pair of wireless headphones and a vape pen.

Police Lt. Jason Johansson said the video of the brawl shows the victim 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.”

He called the video “very void of humanity” and said the victim was not defending himself as he was being attacked.

Lewis was hospitalized with severe head trauma and other injuries and died a week later, according to the coroner’s office in Las Vegas.

In Nevada, a teenager accused of murder can be charged as an adult if they were 13 or older at the time of the alleged crime. But they are entitled to a hearing known as a certification hearing, when a family court judge weighs evidence and the teen’s history before deciding whether they will be transferred to the adult court system.

Teenagers 16 or older accused of murder in Nevada can be charged as adults without first having a certification hearing. That’s why a judge last week transferred the cases of the four older students. Police records show that one of them turned 16 on the day of the fight.

Robert Draskovich, who has been appointed to represent one of the 17-year-old students, said Tuesday that videos of the fight shared on social media are “incomplete.”

“I’ll be going through all the videos with my investigator to see what really happened,” he said.

Police homicide Lt. Jason Johansson said they believe the headphones and vape pen had been stolen from the victim’s friend earlier in the week, which resulted in the students agreeing to meet in the alleyway to fight.

Detectives think the victim wasn’t originally targeted for the brawl, but he walked to the alleyway with his friend after school, Johansson said.

On a fundraising page created to help with funeral and medical costs, the victim’s father, Jonathan Lewis Sr., said that his son was attacked while standing up for his friend. The father has not responded to requests for an interview.