Montreal police (SPVM) say four teenagers were stabbed outside John F. Kennedy High School in the citys Villeray—Saint-Michel—Parc-Extension borough on Thursday.

Police say the stabbings happened during an altercation involving a large group of teenagers at around 1 p.m. in an alleyway in front of the school on Villeray Street.

When officers arrived, they found a 19-year-old man with stab wounds to his upper body who was sent to hospital. Police are waiting for an update on his condition.

Another teen, also 19, was stabbed in the hand but did not require hospitalization and is out of danger.

Later, police learned that two teen boys aged 15 had gone to hospital on their own with stab wounds. Police spokesperson Const. Jean-Pierre Brabant said the two 15-year-olds were later arrested.  

Of the four people stabbed, three are considered out of danger. 

The school was put on lockdown but it has since been lifted.

Brabant said part of the altercation was filmed and that a recording is in the hands of investigators, but they are looking for more footage.

The more video we have the better idea we have of who was involved and if we can identify potential suspects, he said.

Witness said friend lost a lot of blood

Anthony Bass, a student at the school, told CTV News that there was a group of students hanging out in the alleyway when they were confronted by another group of four males coming to attack us.

They were like, whats up, whats up? One of my friends, they grabbed him, and they pulled back, and one of the guys pulled out a knife and stabbed him right in the hand. His hand is, like, all cut up. We could see his bone and everything. As soon as I came up, they started running, he said.

Its sad to see this go down. I never imagined this could go down … It was a lot of blood he lost.

Witnesses and neighbours told CTV News that there was another large altercation Wednesday in the same alleyway around noon that was also filmed.