The teen, whose name was not released, was rushed to hospital at around midnight and underwent emergency surgery.
Police say as many as 20 people were involved in the fight on the school grounds at 1001 Cotton Drive. They are recommending an attempted murder charge against a 23-year-old man.
Sgt. Randy Fincham says it doesn't appear to be gang related, but investigators aren't sure what sparked the incident.
"We don't know, that's something that investigators will look at today to try and determine exactly what started this fight, or led up to this young boy being slashed," said Fincham.