TORONTO -- To honour the memory of a young man who died after being shot by police, take action, not vengeance and be strong, not sorrowful, his sister urged mourners at his funeral Thursday, as their grief-stricken mother sat hunched over the open casket.

Sammy Yatim's mother reached out to touch him a few times as friends and family remembered the 18-year-old as a sweet, soft-spoken young man.

Yatim was killed early Saturday on an empty streetcar in an incident that was captured on surveillance and cellphone videos.

Shouts of "drop the knife" can be heard as a few officers surround the streetcar. Three shots ring out and Yatim can be seen dropping to the floor, then seconds later six more shots can be heard followed by the sound of a Taser.

Witnesses have told various media outlets that Yatim exposed himself and waved a knife around before the other streetcar passengers fled.

Yatim's death has sparked public outrage over police use of force and prompted hundreds of people to take to the streets early this week calling for justice. More than 30,000 people have signed an online petition calling for criminal charges to be filed against the officer who fired the shots.

His teenage sister Sarah said her brother is not the first person to die in such a way, but she urged mourners and supporters to make him the last.

"I really want to stress that we're not against the police, we're only fighting against those who killed him," Sarah Yatim said, wearing a shirt with her brother's photo on it and the words, "9 shots...?"

"We're all full of anger, but just because we're mad doesn't mean we wish the same thing upon the man who killed my brother. So please everybody, let's be strong. Pull yourselves together. Stop with the tears and get started with the action. Let's make Sammy proud."

She began her eulogy by reading a poem about what she would say to her brother if she had just a little bit more time with him.

"If I only had five minutes the night you passed away I'd give you one last hug so tight and see your green eyes sparkle," Sarah Yatim said. "I'd tell you that I don't think I could live without you. Not even for a while."

Sammy's spirit lives on and is what is pushing her to fight, his sister said. But if he could talk, he would have told her to change the clothing he was to be buried in and asked her to play some rap music at the funeral, she said.

The priest presiding over the service, however, suggested that not all was perfect in Yatim's life when he died.

"His father dedicated the last three years or more to be next to him, protect him and hopefully guide him to find a better career and pursue his education," said Rev. Estephanos Issa of the Syrian Orthodox Church.

But in the last few weeks Yatim had chosen to discover "his own world" and "a group of friends and the type of life" that he wanted to have, Issa said, adding that it was in those "dark moments" that he died.

The Special Investigations Unit -- the province's police watchdog -- is looking into what happened on that streetcar and if the officer who fired the shots should face any criminal charges. Toronto Police Chief Bill Blair has also said his office is reviewing the incident.

Const. James Forcillo has been suspended and the Toronto Police Association president is urging the public not to jump to conclusions.

Ontario's ombudsman, meanwhile, is questioning whether it is time for the government to review police de-escalation guidelines. Andre Marin has ordered a "case assessment" to determine if a full-fledged investigation into those guidelines is necessary in the wake of Yatim's death.

At a time when there are still so many questions, Issa said he wanted to convey a message of love and forgiveness.

"I haven't heard one single word from the mouth of the parents or the sister that expresses rage or revenge against the police officer who did the shooting," he said. "They wanted to know the truth. They're still eager, searching for clues, trying to make sense out of this."

Most people have come to know Sammy Yatim as the young man on a streetcar holding a knife, but that misrepresents his life and gives an "untrue" impression, Issa said.

He was from a well-respected family, with a father who is a management consultant and a mother who is a pediatrician. Yatim came to Canada four years ago from Syria, where he attended a private Catholic school, played basketball, loved to paint and entered some of his work in local festivals, Issa said. He was an active young man and also took music classes, learning to play the guitar.

"He was very shy, very sweet," Issa said.

A few of Yatim's friends, who didn't give their names when they gave their eulogies, remembered him as a quiet, kind young man.

"He had one of those smiles that would automatically make you smile too," a young woman said. "All you could see in his eyes was innocence. He might have had the tough guy appeal but he was such a sweetheart on the inside. I know he wouldn't hurt anyone, not even on his worst day."

Another friend recalled Yatim's smile, which he said didn't come often, but when it did, it was huge.

"He was always very soft-spoken, never said anything bad to anybody at all," he said.