An autopsy performed on a teenaged boy who died after a fist fight in a Quebec high school cafeteria last week shows he died after suffering a ruptured artery that stemmed blood flow to his brain.

But officials with the Quebec coroner's office said it's not yet clear whether the artery ruptured because of the head punch.

Jean-Benoît Beaulieu, 14, died April 25 after he was punched in the head during a fight that broke out at École Secondaire Arc-En-Ciel in Trois-Pistoles, about 250 kilometres northeast of Quebec City.

Another teenager who was charged after the fight has pleaded not guilty to manslaughter.

The teenager returns to court July 5.