A 16-year-old male has been stabbed inside a Toronto high school in the city's east end.

Police are investigating whether robbery was the motive in the attack.

Police were called to Eastern Commerce Collegiate Institute at around 3 p.m. where they found the victim suffering from a stab wound to his stomach.

The victim has been rushed to hospital and has since been listed in serious but stable condition.

One student told CTV Toronto she saw the victim minutes before he was attacked.

"I saw the kid sitting on the floor," she said. "He was doing his homework."

The school, located in the Pape and Danforth Avenues area, was in lockdown for about an hour while police investigated the incident.

A lockdown effectively prevents anybody from coming into the school or leaving the premises without police permission.

"We were told to stay in our classroom," one student said about the lockdown.

Once police deemed the area safe, the lockdown was lifted and students were allowed to leave the property just before 4:30 p.m.

"Once we heard the lockdown was over, you could see a lift off our shoulders and our faces," said another student. "We could call our parents to tell them we are okay."

There are no suspects in custody but police sources say they are looking for two people.

Police are not sure if the two suspects are students at the school.

With a report from CTV Toronto's Austin Delaney