Orange and white ribbons were tied to an oak sapling planted in memory of murdered schoolboy Jaden Moodie, 14, at a ceremony on Friday, as balloons in the same colours were released “to lift his spirit”.

Until last summer, Jaden lived in Arnold in Nottingham where the tree planting ceremony to mark his death took place on a sleet sodden slope in Arnot Hill Park.

Dozens of Jaden’s friends from his old school, Redhill Academy, wore T-shirts bearing Jaden’s photo with the words “gone but never forgotten’’. They huddled together against the biting wind and spoke little, as Jaden’s family and other members of the community wept and tried to console each other.

The teenager was deliberately rammed by a car while riding a moped in Leyton on 8 January, not far from his grandmother’s home in Waltham Forest, east London. He was then stabbed repeatedly by three men travelling in the car, a black Mercedes class B, in a frenzied 30-second attack.

Jaden’s sister Leah Moodie-Green speaking at the ceremony. Photograph: Fabio de Paola/The Guardian

Jaden’s death was particularly horrifying because of the brutal nature of the attack and the fact that he was so young when he died. He is the youngest person to die in a street attack in the capital in more than a year. Ayoub Majdouline, 18, has been charged with his murder.

His family paid tribute to Jaden whom they describe as “our beautiful boy”. They have vowed to try to stop the cycle of violence leading to the deaths of so many teenagers and young men and have launched a foundation in Jaden’s name to try to provide more support for young people.

“We do not want any other family to experience the pain and grief of losing a child, that is why we are saying enough is enough,” said Jaden’s 18-year-old sister Leah Moodie.

“We are launching the Jaden Moodie Foundation to celebrate Jaden’s love for life and to support young people with fulfilling their potential. We will be working with people from all walks of life, from grassroots to policymakers, to ensure that there is no more tragic and unnecessary loss of young lives.

“We need to save our streets and save young people just like Jaden who have ambitions, dreams and a whole life to live. We need to help them to live.”

Leah Moodie said Jaden was a thoughtful boy who was always aware of those who had less than him.

Jaden Moodie. Photograph: Family Handout

Jaden’s aunt Tesfa Green said: “Jaden’s loss is a huge and devastating one for our family. He has left a gap that will never be filled. The only thing that can bring us comfort as a family is justice for our boy.”

Leah read out a tribute to her brother at the short and simple ceremony in the park. She spoke of his infectious smile, caring nature and passion for motorbikes. He dreamed of becoming a boxer and wanted to travel the world when he reached 16.

“Jaden did not get a chance to travel the world or to become a boxer,” she said. “Though his time was short he has given me and my family the most amazing memories. Jaden is gone. Our lives will never be the same again.”

Vernon Coaker, the Labour MP for Gedling, in Nottingham, attended the ceremony and said that killings like Jaden’s were not just an issue for the police to address but a matter for the whole of society. “This is a national emergency, a national crisis,” he said.

In London, homicides last year reached more than 130 – the highest level for a decade – and included 75 stabbings and 13 shootings.