Screenshot from cellphone footage showing the fight at Sylmar High School in Los Angeles on May 9, 2016

Security at Sylmar High School in Los Angeles increased Tuesday after a huge fight involving some 40 students took place on school grounds Monday, the Los Angeles Times reports. 

Cellphone video shows the chaos that ensued during the 20-minute fight as students ran around trying to hit one another. Twelve officers were required to bring the situation under control. 

School Principal James Lee confirmed that students were involved in the fight and that "disciplinary action" had been taken. Students' parents have also been notified about the incident. According to the Times, it's not clear what started the brawl, but the Times notes that students told news station KTLA that race and a dispute over the prom may have caused the tension. 

According to the Los Angeles Unified School District, police are investigating the incident and additional school police, counselors and administrative staff will be present on campus Tuesday. 

"We want to reassure parents that the safety of all students and staff remains our top priority," district Superintendent Michelle King said in a statement.

Read more at the Los Angeles Times.