Thousands of Australians have turned out for vigils in towns and cities across the country to mourn the death of Noongar-Yamatji schoolboy Cassius Turvey.

A 21-year-old man has been charged with murder after the alleged attack when Cassius and his friends were walking home from school in Middle Swan on 13 October. He died from injuries sustained during the attack 10 days later.

Dozens of vigils and rallies in his memory were held around the country on Wednesday with an estimated 3,000 people turning out to show their support in Sydney at the Town Hall.

In Perth, his mother led the vigil in centre of the city as thousands gathered to grieve and mourn the loss of the teen.

Mechelle Turvey gave a powerful statement, speaking of her pain and anguish and thanking the country for their support.

“The love, the generosity, the kindness, and the outpouring of tributes across the nation has been so appreciated,” Turvey said in a statement.

The year 9 student was known for his love of basketball, running a lawn-mowing business and helping his mates with their schoolwork. “He was the heart and soul of the community,” Turvey said.

She urged the community to come together as they mourn but warned against any forms of violence in the wake of her son’s death.

In Sydney an estimated 3,000 paid their respects to Cassius and the family with a smoking ceremony, speakers and a moment’s silence.

Yamatji actor and performer Ernie Dingo urged the community to come together and tackle racism.

Many attendees carried candles, wore black T-shirts bearing the teenager’s face with “forever 15” and “Kids matter” on the back, while others wore the black, yellow and red colours of the Aboriginal flag or carried signs and placards in memory of Cassius for justice.

Cassius’s cousin Leon Turvey, who attended the vigil in Sydney with his teenage sons, told Guardian Australia he was overcome by the support shown by ordinary people from across the country.

“We have all the other Aboriginal mob, Koori mob and the Wadjallas [white people in Noongar] supporting us here and showing us their love and kindness and respect to us and all the family back home.”

He said Cassius’s death had reverberated across the country with many Aboriginal parents having to have difficult conversations.

“This triggers a lot of emotions inside of us, it’s not easy to handle and deal with and a lot of our people I’ve been talking to their own children about this and what’s happened,” Leon Turvey said.

Lizzie Jarrett, one of the speakers at the Sydney rally, criticised comments made by Western Australia’s police commissioner suggesting Cassius had died because he had been in the “wrong place”.

“No Black child is ever in the wrong place, at the wrong time, on their own land,” she said to loud clapping.

Amongst the thousands of attendees in Sydney, Abby Lee Lewis and Jayla Memarloo comforted each other through tears; they never knew Cassius but his death had hit them hard.

“I grew up in WA, and spent more than 17 years there and I’m here because my heart goes out to the Noongar community. We’re here in support and solidarity,” Lewis, 33, said

At the end of the Naarm/Melbourne vigil held at the Aboriginal Advancement League in Thornbury, a group of 15- and 16-year-old Indigenous boys from Crow Youth boxing club spoke of how Cassius’s death had made them fearful to go out.

“I’m a 15-year-old boy just like Cassius,” one said. “I’m in my school uniform and I deserve to get home safe.”\

A few thousand gathered outside on the hill surrounding the hall. Among those paying their respects to Cassius included the federal Greens leader, Adam Bandt, and Greens Senator Lidia Thorpe.

For the adults who spoke, there was a collective pain and grief that it could happen “anywhere, anytime, on our country”. “We know that Cassius had a big heart, he was generous, he was proud of his culture,” one speaker said.

Rallies and vigils in Cassius’s honour were also held in Adelaide, Brisbane, Hobart, Alice Springs, Darwin, Adelaide and many regional towns and remote communities around the country.

Megan Krakouer, of the National Suicide Prevention and Trauma Recovery Project, who has helped with planning and organising many of the vigils, said there were 44 confirmed rallies across Australia with events also being held in the US and New Zealand.

“That just goes to show how far and wide the impact of his death and his life has gone, it’s reverberating around the country and the world,” Krakouer told Guardian Australia.

She thanked attendees but also urged the country to come together and acknowledge the harm racism and violence can have on children.

“This is impacting our kids, black, brown and white and especially the most marginalised and vulnerable communities. We all have a right to feel safe.”

WA police have said they are investigating allegations of racial slurs being used but have made clear they are not speculating about possible reasons for the alleged murder. They have said they believe a metal pole was used in the assault.