A teenager was taken to hospital with serious injuries after a fight near Western Canada High School on Thursday afternoon.

Police and emergency crews were called to the school at 17th Avenue and Fifth Street S.W. at about 12:30 p.m., said EMS spokesman Adam Loria.

Another male student was treated at the scene.

Witnesses told CBC News there was an altercation between two groups and that the boy who was seriously injured was trying to break up the fight when he was attacked.

One Grade 10 student who saw the altercation said he saw a crowd of more than 100 youths, and some were fighting.

Victim 'stomped on'

"The kid who got hit, or is in the hospital, he got stomped on the head after trying to break up one of the fights," the student said.

"It was really scary. We went back to school after that, we didn't want to be here. We didn't want any part of it."

​The school's principal, Martin Poirier, sent an email to parents notifying them about the incident, which he said happened off school property behind a restaurant on 17th Avenue.

"Each situation that arises requires an appropriate level of response to ensure the safety and security of students and staff," he said.

"School staff is monitoring this situation closely, and, if necessary, we will enact other critical incident protocols or procedures. Keeping all students safe at school is our priority."

Calgary police say the incident is under investigation but so far no charges have been laid.