SYLMAR, Calif. – It took a dozen Los Angeles Unified School Police to break up a massive student brawl at Sylmar High School Monday that was caught on video and posted to YouTube.

About 40 students participated in a brawl that lasted approximately 20 minutes during lunch time at Sylmar High School Monday, NBC Los Angeles reports, though the crowd in the video is much larger.

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The YouTube video shows several black student kicking and punching a white or Hispanic student on the ground, before police and school officials step in. Other fights throughout the school’s courtyard also involve black students pummeling what appears to be Hispanic students.

In one fight, police pull several black students off of another student they’re beating on the ground, and other black students step in to continue to kick the victim on the ground.

One black student who was restrained by police continued to taunt his victim, who was in the fetal position on the ground: “What’s up! What’s up! What’s up!”

NBC Los Angeles reports a dozen school police officers were dispatched to the school to break up the fight, and other adults also appeared to step in. At least two videos of the melee taken from student cell phones were posted to YouTube, and principal James Lee sent an email notification to parents.

“Multiple sources tell NBC 4 tonight this brawl today may be retaliation for an incident over the weekend in which a student was hit in the head with a bottle at a senior prom after party,” reporter Beverly White said, adding that school officials won’t discuss the incident because of “student privacy rights.”

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“One kid, he just starting going up to the other kid, he like took the first punch or whatever,” an unidentified student told the news site. “That’s how it all started. Everyone just starts to back up their friend.”

“I tried to pull my friends back and tell them to leave,” another unidentified student said. “They’re my friends, I don’t want them to get hurt. It could escalate to someone getting shot.”

Principal Lee’s statement to parents contends “disciplinary actions have been taken” against students involved in the brawl.

“Their parents have been contacted and the investigation continues,” it read, according to KTLA.

The fight at Sylmar is one of several at the school posted to YouTube in recent years.

It also follows the recent death of Delaware student Amy Joyner-Francis, who was allegedly pummeled to death by three of her classmates in the bathroom at Howard High School of Technology in Wilmington, ABC 6 reports.

The 16-year-old victim had a previous heart condition that was aggravated by the attack, according to the medical examiner’s report.

“Amy died from a cardiac incident that she was vulnerable to because of pre-existing heart condition, but the cardiac incident would not have occurred if she had not been assaulted,” the report read.