(CNN) -- Four people reportedly have been stabbed at St. Joseph's High School in Mississauga, a suburb of Toronto, in Ontario, Canada.
Sgt. Zahir Shah, of Peel Regional Police, said police were called to the school at 8:28 a.m. for a dispute. He said he could not comment further.
Local television stations are reporting that a stabbing happened inside the high school and a teacher possibly was involved.
Shah says three victims were taken to a hospital, and another was flown to a trauma center. He would not comment on the severity of their injuries.
"This morning, our school was placed in lockdown as a result of a serious incident involving some St. Joseph students," St. Joseph's Principal Frances Jacques said in a letter to students and staff.
"Police are investigating ... School staff is co-operating with the police investigation, but because this is an active investigation, we are unable to provide further details."
Shah said "two young offenders" are in police custody.
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