Three youths have been found guilty in the 2015 stabbing death of Burnaby teen Luka Gordic.

A judge found two young offenders guilty of manslaughter Friday and a third guilty of second-degree murder. Because they were 17 at the time of the offence, they cannot be named, but Crown prosecutors have said they will be seeking adult sentences.

Gordic, 19, was visiting Whistler for the 2015 May long weekend when police say he was swarmed by 10 teenagers and stabbed.

It took B.C. Supreme Court Justice Terence Schultes hours to read out his decision on Friday. Extra security and officers from the Vancouver Police Department were on hand, keeping watch over tension between Gordic's family and the families of the accused.

When Schultes finally pronounced the three young men guilty, the courtroom broke out into shouting, as well as some pushing and shoving.

Outside the courtroom, the victim's mother, Clara Gordic, was pleased with the decision.

"I'm so happy that the judge saw through them — a bunch of lies. I just can't believe it," she said. "This was a planned attack."

A fourth young man was previously convicted in the killing.  Arvin Golic, who was 18 at the time, was tried as an adult and is now awaiting sentencing for manslaughter.