The death of model Reeva Steenkamp underlines that South Africa is battling with a deep-rooted culture of violence, the Gandhi Development Trust say.
"This culture of violence exists beyond race, religion, culture or social status," the organisation said in a statement.
The Gandhi Development Trust called on South African men to "do their part" and act against gender-based violence.
"It is of grave concern that the death of Steenkamp comes in the midst of the national focus of violence against women and children."
"We hope the police will find the truth behind Steenkamp's death and that the justice system will act swiftly."
Athlete Oscar Pistorius, 26, who is accused of murdering his 29-year-old girlfriend Steenkamp, was arrested shortly after the fatal shooting at his Pretoria home early on Thursday morning.
He has since been charged with Steenkamp's murder and is expected to bring a formal bail application when he makes his second court appearance on Tuesday.