The Stearns County Attorney’s Office filed criminal charges Thursday against 19 students involved in a large-scale fight that led to a lock down at St. Cloud’s Tech High School Sept. 25.

All of the students, who live in St. Cloud and range in age from 14 to 17, were charged with second- or third-degree riot. A 16-year-old boy who was carrying a pocketknife also was charged with possessing a dangerous weapon and terrorist threats. Four of the students also face charges of aiding and abetting an assault.

Police say one student suffered a broken nose in the fight, which started about noon in a hallway when two 16-year-old boys who had been involved in a previous altercation off school grounds confronted each other. The teens were the same race, Assistant Police Chief Jeff Oxton said earlier this week in a news release.

Over a 10-minute period, additional fights involving a growing number of students erupted at other hallway locations. School staff who tried to stop the brawl were ignored. Three employees received minor injuries, Oxton said.

About 20 police officers were called to the high school to break up the fight.

School officials have said that none of the students will be allowed back at the high school this year and will face disciplinary action “up to and including expulsion.”