He loved art and photography and was a great cook - and he was brutally stabbed to death.

These were the memories that triggered sobs and drew tears as mourners gathered at a sombre memorial service on Friday for 19-year-old Kulani Mathebula.

Mathebula was killed just minutes after leaving home to go to Mondeor High School in the south of Johannesburg on Wednesday. The cries of his mother pierced the silence of the quiet suburb when she saw his body. "My one and only child! Why did they have to take him away from me?" Dumi Chauke cried.

The school hall was packed to capacity for his memorial. There were flowers. There were photos. And hand-written messages: "Are we safe?" asked one. "No more violence!" implored another. "Justice 4 Mathebula", read another.

He was described as a humble child by pastor Elizabeth Khosi.

"I was shaking when I heard the news because I knew him so well. He was a humble boy," she told mourners.

Khosi said Mathebula's death had not been in vain. "God took Khulani's life to put an end to the killings," she said.

Khosi called on parents and pupils to unite in prayer and said pupils needed healing.

"School children you need to heal from anger, rebelliousness and bitterness ... you need forgiveness and to seek God for a fresh start," she added.

A grade 8 pupil described Mathebula as a brother. "He did not deserve to leave the world like this. He was another victim to a hectic crime, who is next? Are we safe?” she asked in a letter.

Mathebula's family voiced their unhappiness at how long it took some authorities to attend to the murder scene.

"I cannot leave without mentioning something that does not sit well with me. It took at least four hours for forensics and a mortuary van to arrive ... Why would it take four hours for forensics to arrive? We are in Johannesburg, in a suburb. The blood had dried up and flies were surrounding him," said his uncle, Mikangelo Chauke.

Chauke said the family was battling to come to terms with the death of their loved one because he was an innocent child.

"Kulani would never get involved in a fight with anyone. He was an innocent kid, anyone who has come across him can attest to this."

A community member and father of two teens said he was heartbroken by the ordeal. "My heart is bleeding inside, I feel like this is my son as well."

He called on the community to come together and fight against similar crimes in the area.

Gauteng education MEC Panyaza Lesufi said at the service that he was sad that the family was being presented with a death certificate instead of a school report.

Lesufi applauded police for making a breakthrough after arresting three pupils in connection with the gruesome murder.

He pleaded with pupils not to resort to violence to solve their differences.

Mathebula will be laid to rest on Sunday.

Thank you for apprehending those learners but it was too late because a life had already been lost," he said.

He pleaded with pupils not to resort to violence to solve their differences.

"Please, please let us not resolve our differences through violence. 

"Go well my boy, we will have peace and tranquility in this country one day," were Lesufi's last words for Mathebula.

Mathebula will be laid to rest on Sunday.