Four teenage boys were arrested Wednesday on suspicion of assaulting a high school student boy last month, police said, after a video showing the boy being hit and kicked went viral on social media.

The four boys, all 16 years old and living in the city of Niigata, allegedly injured the 16-year-old student's head and waist in mid-February, the police said. The student reported the incident to police on Feb. 19.

The video showed more than four people kicking the victim or hitting him with a stick, but the police have concluded that the four boys arrested played major roles in the assault.

Two of the four and the injured student attend the same high school in the city, while the other two left school last year, according to the school. The video was filmed on a beach near the school on the evening of Feb. 15.

The school came to know of the video last month after receiving a report from a member of the public.