Dozens of family members and friends of a teen killed in Whistler last year packed a Vancouver courtroom on Monday as a trial began for three youths accused in his death.

Court heard 19-year-old Luka Gordic died after being swarmed by up to 15 attackers in Whistler Village just after midnight on the Sunday of the May long weekend in 2015.

Gordic’s attackers punched, kicked and stabbed him. The fatal blow was a stab to the heart.

The youths on trial were arrested within minutes of Gordic's death, and a fourth person was arrested later on in the investigation. He will stand trial on his own next year.

Hearing the details of Gordic's death was emotional for nearly 50 of Gordic's loved ones who gathered in court for the first day of the trial.

The teen's uncle, Mike Gordic, said the victim had been very close to his family before his death.

"He was a good kid,” he said, fighting back tears. "He would give you the shirt off his back. He would help you any way he can. And when that happened, it was pretty hard. And it's hard now."

Crown Counsel Henry Reiner said it was "perfectly understandable" that the family would be upset as the trial begins.

"They've been waiting a long time for their day in court," he said.

Most of the friends and family wore black T-shirts reading "Justice for Luka," but were warned not to wear them again as the trial moves forward. The judge said he felt the T-shirts were inappropriate for the courtroom.

Gordic’s uncle says he will respect the judge’s wishes but plans to keep wearing the T-shirt outside of the courthouse.

"I plan to be here for the duration of this trial and I bet you there's a lot of different people who will be showing up,” Mike said.

A large crowd of the victim’s supporters came face-to-face with the three accused as they waited to go through metal detectors to get into the courtroom.

"It's just like a horrible feeling. Your heart drops when you see them. You don't know what to do. You don't know how to react. It's pretty bad,” said Danijela Gordic, the victim’s cousin.

The three accused, who cannot be named because they were under the age of 18 at the time of Gordic’s attack, all pleaded not guilty.

Two face manslaughter charges while the third is charged with second-degree murder.

Lawyers for the Crown say they will call 43 witnesses during the five-week trial, including DNA and blood splatter experts, along with people who actually saw the attack.