Nine Florida high school students — one just 14 — have been arrested after a disturbing video caught them viciously beating a classmate who stopped them from bullying a girl in the cafeteria, according to police.

The students at the ironically named Harmony High School were seen being led away in cuffs after the 17-year-old boy filmed being battered needed 11 stitches in his head.

“This was a serious attack,” Captain Kimberly Montes of the Osceola County Sheriff’s Office told Fox 35 — calling the accused kids “cowards” who should be tried as adults.

“This was not one-on-one, two-on-one — this was nine students against one, and we’re just lucky he didn’t receive more serious injuries than what he got,” he said.

“We tell kids all the time, ‘Stand up for somebody else!’ It takes a lot of courage to do that. He did this and these nine students that beat him up are the ones that are cowards.”

The victim had first stepped in to tell bullies to stop throwing carrots at a girl, sparking an argument with two of them before he left the cafeteria with the girl, officials told he outlet.

One of those involved then jumped him as he walked toward his car after the final bell, with eight others joining in the vicious beatdown, according to cops.

Chaotic cellphone footage obtained by Fox 35 shows students raining blows on the victim while others can be heard screaming and egging each other on.

The victim’s girlfriend broke up the fight. He was then taken by his mother to the hospital where he received 11 stitches on his face, according to police.

Police identified the nine suspects by the cell phone video.

Two 18-year-olds, Quianelle Antonio Reyes-Cintron and Bryan Alexander Ramirez, were booked into the Osceola County Jail.

The seven others — a 17-year-old, five 16-year-olds and a 14-year-old — were taken to the Juvenile Assessment Center. But the sheriff called for all nine to be tried as adults.

All nine were charged with felony aggravated battery and felony inciting a riot, authorities said.

Osceola County School District Superintendent Mark Shanoff condemned the attack and said violence would not be tolerated on or off campus.