A 17-year-old Cornwall youth has been charged with first-degree murder in the death of a 16-year-old student who died after he was allegedly stabbed in a classroom at an alternative high school in Cornwall, Ont. Monday.

The teen, whose name cannot be released under the Youth Criminal Justice Act, is being held in custody in Ottawa and will make his next court appearance May 20.

The flag at T.R. Leger School at the St. Lawrence College Campus flew at half mass Tuesday and students grieved publicly over the tragic loss of their classmate.

Classes at the high school were cancelled Tuesday but the school remained open for staff and students in need of counselling. School officials say counsellors will remain on campus until they are no longer needed.

Meanwhile, the school continues to be treated as a crime scene as police comb school grounds for evidence.

Police locked down T.R. Leger School for about an hour on Monday while they investigated an altercation between two students.

Police say the youth in custody was spotted leaving the school, running along a bike path following the incident. He was arrested without incident near McConnell Avenue after a short foot chase by a community patrol officer.

Although an arrest was made quickly, police are releasing few details about the incident.

"I can't get into specifics about it. It's sufficed to say it was an altercation between the two and a 16-year-old was allegedly stabbed," Blake Paquin of the Cornwall Police told ctvottawa.ca on Monday.