Teens charged with murder in schoolmate’s beating death in Las Vegas have been formally charged with second-degree murder.

A fight broke out in an alleyway near his school, where as many as 10 of Jonathan Lewis Jr’s classmates surrounded him.

Nine students have been arrested in total, police said.

Nevada law will allow the first four to be tried as adults, even though they are under 18 years old.

The charges against Dontral Beaver, 16, Damien Hernandez, 17, Treavion Randolph, 16, and Gianni Robinson, 17, were read in court on Tuesday.

The fight was captured on video and shared to social media on 1 November near Rancho High School. A brawl broke out over headphones and a vape pen stolen from the victim.

Jason Johansson, homicide lieutenant for the Las Vegas Metropolitan Police, declined to show the video to the press, describing it as “very graphic” and “devoid of humanity”.

Jonathan was swarmed by 10 students shortly after taking his shirt off to prepare for the fight, according to the video.

After the victim has been pulled to the ground, the teens kick, punch and stomp on him, Mr Johnson said.

One of the students brought the unconscious victim back to school after he was found by a member of the public. Attempts were made to revive him by school staff and he was later transported to hospital.

According to police, the teenager died six days after suffering a traumatic head injury that was not survivable. His death was determined to have been caused by blunt-force trauma by a post-mortem examination.

Nine students, aged 13 to 17, have been arrested. Police are still working to identify them all.

All those who have not yet been charged are awaiting separate court hearings because they are all under the age of 16.