Toronto police are searching for a young man who fired a gun during a confrontation inside a downtown high school, sending the building into lockdown Thursday afternoon.

Three other young men were questioned on Thursday, after officers were dispatched to Central Tech high school, near Harbord and Bathurst Streets, when a suspect pulled a gun in a stairwell.

Toronto Police Const. Wendy Drummond said three teens were in a stairwell when one of them became involved in a confrontation with a fourth teen and someone fired the gun. No one was injured in the shooting.

Drummond said the group scattered; two were located at the scene while the other two fled. A third was arrested later in the day but police determined him to be a victim in the incident.

The school was locked down for the remainder of the afternoon as officers searched the school. Classes resumed at Central Tech Friday morning.

Drummond said the suspect is still at large. He is described as a 17- or 18-year-old black male, 6'0" with a medium to skinny build.

Police said one person questioned following the incident has been charged, but not in relation to the shot fired inside the school.

They would not say what the charge was, only that it was not related to the shooting. The other individuals questioned on Thursday were released without charges.

Police believe there are more witnesses to the incident.