TORONTO -- A group of mothers who lost their sons in police shootings added their voices Tuesday to a growing chorus calling for the death of an 18 year old to change how police respond to people in crisis.

Hundreds of protesters waving banners and placards gathered outside the city's police headquarters demanding justice for Sammy Yatim, who died last month after being shot and Tasered by police on an empty streetcar.

Nine shots can be heard on cellphone videos that captured the incident, following shouts for Yatim to drop a knife. The final six shots appear to come after he had already fallen to the floor of the streetcar.

Yatim's mother and sister along with the families of other police shooting victims in Ontario attended the protest, which coincided with a monthly public meeting of Toronto's police services board.

"Justice for Sammy, justice for all," chanted protesters, who were blocked from the police headquarters' entrance by officers on bikes as they called for the officer who shot Yatim to be charged and put in jail.

Not long before the demonstrators spilled into the streets, a group of mothers who had their sons killed by police appeared together at a news conference. They said they had been "re-traumatized" by Yatim's shooting death.

"It was too close to home," Jackie Christopher said with tears streaming down her face.

Her son, O'Brien Christopher-Reid, was killed in 2004 after Toronto police responded to a call about a man with a knife in a park. Officers tried to pepper spray the 26 year old, but he pulled a knife from his pants and held it over his head, the Special Investigations Unit found.

He moved toward them, shouting either "We're all going to die" or "You're all going to die" and three officers fired a total of eight shots, hitting Christopher-Reid three times, the SIU found.

His mother sat through every day of the coroner's inquest into his death and said if the recommendations that came out of it were followed, Yatim would be alive today.

"What's the point of all of this if nothing's going to happen?" Christopher said. "Do I sound angry? Yes, I am angry. I'm angry because another mother lost her 18-year-old son at a time when it should not have happened."

Levi Schaeffer was also wielding a knife when police shot him in northwestern Ontario in 2009. The provincial police officer who shot and killed the 30 year old told the coroner's inquest that he thought Schaeffer was about to kill him.

Ruth Schaeffer said police need to have more of an emphasis on de-escalation rather than using force, but what's needed is action, not more studies and inquests.

"We have studies and reports gathering dust in places all over this country," Schaeffer said.

"We've paid probably millions of tax dollars to have those things done. All the recommendations that need to be put in place to safeguard the life of Canadian citizens are sitting in print for anybody who's interested to implement those things."

Schaeffer scoffed at an announcement Monday by Toronto Police Chief Bill Blair that retired justice Dennis O'Connor would lead a review of police procedures, use of force and police response to emotionally disturbed people in the wake of Yatim's death.

"Bill Blair knows all these reports have been done already," she said. "How dare he decide to have another one and spend all our money."

Blair said after a Toronto Police Services Board meeting Tuesday that some past recommendations about these incidents have been implemented, but that now is the time for a comprehensive review.

The head of Toronto's police services board, Alok Mukherjee, said they have asked Blair to ensure the review is "thorough and comprehensive."

"The board is committed to making the report public in the interest of transparency and accountability," he said.

Ontario's ombudsman is also looking into what kind of direction the provincial government provides to police for defusing conflict situations.

Andre Marin said many coroner's inquests into similar deaths over the past 20 years have made recommendations that are almost "carbon copied from each other," but he wondered what has happened to all the recommendations.

Karyn Greenwood-Graham, whose 26-year-old son died of a gunshot wound to the chest in 2007 as he fled a Kitchener, Ont., drug store with stolen prescription drugs, wearing a mask and holding a utility knife, echoed Marin's remarks.

"We cannot any longer accept the way people are gunned down while in crisis," she said. "It's got to be a more human response, it really does."

How frontline officers handle dangerous situations and what force they use is expected to remain in the spotlight over the coming months.

A coroner's inquest into the deaths of three people -- who may have had mental health issues, and were shot and killed after approaching Toronto police officers with weapons -- is scheduled to begin in October.