The following video is disturbing.

More from KTLA 5:

An 18-year-old high school student and his 14-year-old sister were arrested Wednesday at Ramona High School in Riverside, authorities announced.

According to the Riverside Police Department, the high school's assigned resource officer was assisting staff with "some student unrest near the end of the lunch break," at around 1 p.m., in which a fight had broken out between a couple of kids. The incident resulted in the school being put into a "lockout," officials added.

Police said that one student, an 18-year-old male, refused to comply with directions from school administrators and the school's resource officer. When the officer attempted to detain the student, he resisted.

The 18-year-old student was arrested for resisting arrest, while his sister was booked into juvie for attacking a peace officer.